It's fairly easy to do. There are four files that you will need.
1. Bell Rom
2. Sprint Rom
3.
Winrar for your computer
4. Ruu.rar from this link:
ftp://ppcgeeks.com/Vogue/Users/rstoyguy/tools/RUU.rar
Here are the steps;
1. Flash the Bell rom to get the radio.
2. Download and install WinRar to your computer.
3. Extract Ruu.rar to it's own directory. (flash utulity)
4. Right click on the Sprint rom in file explorer and select "Open with WinRar"
5. Click on and hold 2.nbh.
6. Drag that into the same directory with RUU.rar and drop it in there...
7. Once the Bell rom is flashed, go into the RUU.rar directory and run RomUpdateUtility which will flash the sprint stock rom.
8. Enjoy!