Today, 10/01/08 I flashed my ROM and got GPS working after a bit of trial and error. It was alot easier than I thought. Start here:
http://forum.ppcgeeks.com/showthread.php?t=24979
After that, go here:
http://forum.ppcgeeks.com/showthread.php?t=30109
If you read carefully, and follow all of the directions, it will work for you.
For your info, I used the official stock Sprint ROM.
Good luck.