I think there is a thread on this topic in the Carrier Discussion sub-forum linked as a sticky..
Found one here in the EVO 4G forum;
http://forum.ppcgeeks.com/showthread.php?t=126988
Hope that helps,
-CC
EDIT: Perhaps and I understand how. Not knowing all the terminology used one might not really understand what CDMA is, but read HTC EVO 4G Upgrades and think.. Hey I upgraded, let me post!