P68's came with CA. P12's and PMI 1 DF's were 12 gram.
there are several options:
drop in front plug with a hose running back to the bottle,
dummy 12 gram and drill a hole in the side of the lower tube to connect the line,
drill and tap the chamber wall directly then solder an 1/8 npt elbow in place,
trade or sell your gun for one set up for CA already.