You could try steaming the wood with a hot iron with a steamer built in, or you could spray it on with aspray bottle. Then you would clamp the wood down to a flat surface and leave it there for a few days to straighten out.
Wait for others answers, but I've used tis method recently.
When I removed the clamps I had the center of the guitar body lined out and the glue on and then glued one half of the maple on. The next day I removed the other piece and glued it on immediately afterwards.
Hope this helps. Good luck. And this should have been put in the "Solid body and Bass chat", but the mods will probably move it for you. So, no big deal.