EDIT: This thread is now obsolete. Instead, all users both Sprint and Boost can use this zip file to flash root to the phone via CWM. Thanks to the hard work of zombu2 for the root installer edits and 2fast4u88 for the CWM port, there is now a faster way of rooting and users can still retain their apps and data. Unlocked boot loader and ClockWorkMod remain as requirements to install this. 
http://androidforums.com/evo-design-all-things-root/562206-working-cwm-root-zip.html
If you have issues with SuperUser denying permissions to everything, force stop Superuser in app manager and clear it's cache. It should then operate normally afterwords.
The information below will remain as a reference point for those developing custom roms.
Note to all users. Once you get CWM installed, the first thing you should always do is run a backup of your phone before changing anything. That way, if something goes wrong, you can reset back to before it happened and not have to worry too much about bricking your phone!
Now on to the rest of the post:
With this CWM backup, Boost Mobile users can now have something to fall back on if they forget to make a backup after a crash or bricking.
However the main advantage is that it comes with root preinstalled and you can easily reinstall your apps and get your phone back to where it was before the restore operation.
I am to assume most of you are already familiar with how to use CWM, so I won't go into full detail on the process of doing a restore.
Requirements:
1. Your bootloader must be unlocked. Go here to find out how to do this. You will need to create an account and login to the HTCDev website before it will let you go through the process of unlocking the bootloader. Do not worry about the Boost version of the phone not being listed. Just select the Sprint version as the process for the two is the same.
2. You must have CWM installed (ClockWorkMod). It is a custom recovery and requires the boot loader to be unlocked in-order to install it. I detailed the process and the file needed to install CWM on your phone here. Don't worry, you don't need root to install CWM.
3. If you just bought the phone, it is best that you activate it first prior to installing any custom roms or this root method.
Now on to the good stuff.
1. Download my factory stock backup below that has root preinstalled with the correct permissions. Extract the zip file you downloaded to the root of your sd card. If you already have a clockworkmod folder, let it overwrite it since all it's doing is extracting a new backup to that folder.
2. Find the restore/backup menu in CWM, then do a restore. Restore my backup and let it finish. After it's done, reboot the phone and go through the process of restoring your personal information and setting up the phone. As a result of how this works you will lose your installed apps and settings when restoring the backup. If you really don't want to do that, then I guess you can follow the Sprint instructions later on in this post to do it the hard way.
3. Profit. You can now install your apps and use your phone.
CWM Stock Restore files for HTC Evo Design 4G (Boost version):
Download Link: (root is preinstalled!)
evodesign4g_boost_backupwithroot.rar
Removed the June update version since the OTA update wasn't applied correctly. (I forgot to relock the bootloader so the radio firmware was not the correct version and the newer rom clashed with it and caused issues with 4G/Wifi not working). This backup is before the update they released this month. Don't attempt to apply their update. If you have CWM installed the update won't install and you'll end up having to do a battery pull. But no harm done.
But if you have an unlocked bootloader but still have stock recovery, you WILL run into problems if the OTA update has a update for a kernel or the radio firmware since nothing in an unlocked bootloader can write kernels or radio firmwares without s-off and that is not yet available for this phone. (Unless you are on Sprint and haven't updated to the last OTA update yet)
All info originally posted below removed as this is no longer the best way to root this phone. (not from backups anyway).
This thread will mainly remain to make a stock backup with root pre-installed available for those who need to restore a phone due to any unforeseen problem they might encounter.
http://androidforums.com/evo-design-all-things-root/562206-working-cwm-root-zip.html
If you have issues with SuperUser denying permissions to everything, force stop Superuser in app manager and clear it's cache. It should then operate normally afterwords.
The information below will remain as a reference point for those developing custom roms.
Note to all users. Once you get CWM installed, the first thing you should always do is run a backup of your phone before changing anything. That way, if something goes wrong, you can reset back to before it happened and not have to worry too much about bricking your phone!
Now on to the rest of the post:
With this CWM backup, Boost Mobile users can now have something to fall back on if they forget to make a backup after a crash or bricking.
However the main advantage is that it comes with root preinstalled and you can easily reinstall your apps and get your phone back to where it was before the restore operation.
I am to assume most of you are already familiar with how to use CWM, so I won't go into full detail on the process of doing a restore.
Requirements:
1. Your bootloader must be unlocked. Go here to find out how to do this. You will need to create an account and login to the HTCDev website before it will let you go through the process of unlocking the bootloader. Do not worry about the Boost version of the phone not being listed. Just select the Sprint version as the process for the two is the same.
2. You must have CWM installed (ClockWorkMod). It is a custom recovery and requires the boot loader to be unlocked in-order to install it. I detailed the process and the file needed to install CWM on your phone here. Don't worry, you don't need root to install CWM.
3. If you just bought the phone, it is best that you activate it first prior to installing any custom roms or this root method.
Now on to the good stuff.
1. Download my factory stock backup below that has root preinstalled with the correct permissions. Extract the zip file you downloaded to the root of your sd card. If you already have a clockworkmod folder, let it overwrite it since all it's doing is extracting a new backup to that folder.
2. Find the restore/backup menu in CWM, then do a restore. Restore my backup and let it finish. After it's done, reboot the phone and go through the process of restoring your personal information and setting up the phone. As a result of how this works you will lose your installed apps and settings when restoring the backup. If you really don't want to do that, then I guess you can follow the Sprint instructions later on in this post to do it the hard way.
3. Profit. You can now install your apps and use your phone.
CWM Stock Restore files for HTC Evo Design 4G (Boost version):
Download Link: (root is preinstalled!)
evodesign4g_boost_backupwithroot.rar
Removed the June update version since the OTA update wasn't applied correctly. (I forgot to relock the bootloader so the radio firmware was not the correct version and the newer rom clashed with it and caused issues with 4G/Wifi not working). This backup is before the update they released this month. Don't attempt to apply their update. If you have CWM installed the update won't install and you'll end up having to do a battery pull. But no harm done.
But if you have an unlocked bootloader but still have stock recovery, you WILL run into problems if the OTA update has a update for a kernel or the radio firmware since nothing in an unlocked bootloader can write kernels or radio firmwares without s-off and that is not yet available for this phone. (Unless you are on Sprint and haven't updated to the last OTA update yet)
All info originally posted below removed as this is no longer the best way to root this phone. (not from backups anyway).
This thread will mainly remain to make a stock backup with root pre-installed available for those who need to restore a phone due to any unforeseen problem they might encounter.
