This looks long, buts its just the initial setup
If you aren't familiar with doing things from fastboot, chances are the first thing you are going to need to do is properly setup the folders to carry out the fastboot flash command. This setup is going to take the most time and after you have it all set up its very quick to do after that.
Setting up ADB:
1) Download the mini-SDK here and move it to something like C:\Android\platform-tools or as instructed here -
ADB Guide (updated 2013/05/21)
adb.exe - Windows adb utility
fastboot.exe - Windows fastboot utility
fastboot-windows.exe - Windows fastboot utility
AdbWinApi.dll - adb link library for Windows
AdbWinUsbApi.dll - adb link library for Windows
These files will be used to push the boot.img (contains the kernel) from a ROM to your phone via fastboot.
2) Download your ROM and open it, it will look like this:
3) Copy the boot.img from the ROM to the same folder as the mini SDK you've downloaded.
4)Plug your phone into the computer via USB and power the phone off. Then press volume down + Power to get to fastboot
5)Once there, we need to open up a command prompt in the location where your sdk-tools are. If you are in windows 7 you can just shift+right click to select "open command prompt from here"
If you don't have win 7 you can manually move to the file location with the command cd to change directory.
6)Once you are in the correct directory you just type in
fastboot flash boot boot.img
and hit enter