I would think it is possible, with fairly minimal modification. Now I can't guarantee this will work, but I can't see why not.
Get one of these:
Stereo Headphone 3.5mm Plug To Dual RCA Plugs Y Adapter Splitter Cable
Then get a stereo harness and do Whiterice's amp integration harness:
D.I.Y. the long-awaited amp integration harness by Whiterice!
Only instead of connecting the RCA's to the speaker wires on the harness, connect the F+R wires on the harness to the L+R RCAs on the headphone jack->RCA connector. Or you could do Whiterice's tutorial exactly as is, and just buy a couple rca Y splitters with female ends.
I can't see why that wouldn't work just fine (though i'm hardly a wiring guru or a car audio guru for that matter. I'm more of a nub

).
You would also have to either connect your amp turn-on into the Remote wire or possibly into the 12V and use a switch if you'd prefer the amp only being on when you want it on.
Either way, seems like alot of work for little gain. I'm assuming this is to save weight?