In short...I'm in the same boat. After purchasing the tippmann phenom x7 I was a little upset regarding the "safe" features of the firing modes. Needless to say, I'm heading down the same path, and while this will likely end up more expensive than buy a new board (or potentially a new gun

), I'm likely to gain useful knowledge about electronics and microprocessors along the way. That knowledge is worth the journey.
But enough about me, on to the good stuff....
I decided to dust off my old oscilloscope and probe the pins as the trigger operates. I figured I would at least be able to spot the power and ground pins and perhaps even the trigger pin. Here's what I discovered in my tests:
If you hold the board with the reset button and LEDs facing you (solenoid on top), the top of the chip should be on the right (there's a little etched circle in the top left of the chip to inicate "top")
Top down (Left side)
1 - VCC Power (approx 9v)
2 - 0v (Digital in/out set to LOW?)
3 - 5v (Digital in/out set to HIGH?)
4 - 5v seems to reset the board when probed (firing is canceled and LED stays solid)
5 - 5v (Digital in/out set to HIGH?)
6 - solenoid trigger (fires the gun) (+5v when firing 0v otherwise)
7 - 5v (Digital input?) - switches to 0v when the trigger is held (but not in pulses like #6) Is this the magnetic trigger relay?
Bottom up (right side)
8 - 0v (Digital in/out set to LOW?)
9 - 0v (Digital in/out set to LOW?)
10 - 5v (Digital in/out set to HIGH?)
11 - Green status LED
12 - Red status LED
13 - 5v (Digital out set to HIGH?)
14 - ground
I can't say for certain that this is the ATtiny20, but I can say that if someone else is able to reprogram the chip without soldering and tippmann burned a T20 into the chip face, chances are we're dealing with an ATtiny20.
Can anyone with more expertise gather any more information from the pin data I've gathered?