How to flash HTC One M9 from sprint to boost

I just got an HTC One M9 and I need to find out how i can flash it over to boost mobile. The phone was originally setup for spirnt. I tried the activation process on boosts site as I already have an account but it wouldn't take any of the numbers I put in. I did some searching but came up with nothing on my end. Could someone recommend a program to use or maybe point me to a DIY write up somewhere?


Did you ever figure this one out as I'm in the same boat? Got the sprint M9 unlocked, but can't put on boost because it's not on their compatibility list. What to do...