I've done it on a couple of my boards. It's really easy if you have PCB rev -02 with the 3 ROMs (M1 N1 P1). You just need to get the punt rom images burned on to three 2716s and replace the ones on the board. I got them from Steph at hobbyroms.
If you have Rev -01 with the PROMs (you could have 6 or 12 depending on which ones they used) you have to remove the PROMS first after that is done you can add the punt ROMs at M1 N1 P1.
Then talk to This Old Game about the new play cards you'll need for the control panel.