[theqizmo]

Although I may be wrong, (lance is right, 99.99% of the time, so wait until he replies) you just need to hook the func that changes the health of the player, and make sure the original func gets bypassed when you want it.

I don't have time at the moment to go tracing down for the original func (if it's even possible, most likely it is possible), but this may help you get in the right direction.