HITP has prone, but it isn't perfect. Even in Version 2, we were not able to fix the POV; nothing in MOHAA script that allows you to adjust POV. But, we can stop you from going prone when it would give an unfair advantage, like in water. HITP is moving to RTCW:ET engine because it's free and we have source code, so we can implement lots of stuff much better. It has prone, too.
I don't know if the beta version is still floating around somewhere. If it is, I'll post the address. If not, the last MOHAA version will be done in about a month.