So I disassembled the eGrip on my X7 classic. Under a sticker on the chip I found the markings of an Atmel ATtiny44. (jackpot!) It is a stock Tippmann board, and from what I can understand the board is very closely related to the Phenom, moreso than the 98c and A5. I also own a 98pro and will disassemble it tomorrow to see if it is the same chip. This project may help a bunch of people if this is correct, not just Phenom users.
I don't have an adequate camera on hand. However, I compared with pictures found online and this is the exact same board, only mine is blue and with the solenoid still soldered on (mine fell off and I had to stick it back on) and a capacitor on the back that reads 6800µF / 10V.
Perhaps it is my calling to port this amazing code to other Tippmann eGrips. I figured I might as well try the X7C first because the board is already soldered back and forth a few times.
Thanks for the links by the way, but I fear the shipping fee is a bit excessive. $30 to ship a $1 chip of negligible weight to Norway seems off-putting somehow. I'll look for the part elsewhere.
Edit: I ordered an adapter cradle for ATtiny chips, the chips themselves and some breadboards from ebay and farnell.