I think so..
a friend of mine has a new honda civic. He bought some audio adapter that gets wired into the front speakers from behind the head unit.
This adapter has RCA slots on it so you can run an RCA wires back to amps. Once a set of RCA's are in the back, you can use an adapter on the rca cables. rca female to dual males. (would need 2 of them) Then you could plug RCA cables to both amps from the stock unit.
After that. normal stuff like power, ground, remote to both amps. then speaker wire to subs or speakers.
This would make sense to me. I have never done it though so no promises it will work.