I have a first cousin gunsmith/gunmaker that bends stocks. He told me how to do it via the infrared lamp method and I've done it to 2 of my SxS bird guns with oil finishes. Never marred the finish or the checkering. Other method is the Hot Oil method. I only know of the 2. I believe the more the figure (dense grain) in the wrist of the stock the harder the job. Using the infrared method it's amazing how pliable the buttstock gets and it may take a couple evolutions of bending to get the dimensions you desire as there is some spring back when the stock cools.
Hunt!ng is spot-on! Allems uses the hot oil method and cautioned me that dense, highly figured woods resist bending and that all wood will "relax" to some degree while cooling. Mine lost about an eighth of an inch of cast but the 5/16" of added cast that resulted was all I needed.
Any wood can be bent using the steam box method. Boat builders use this method all the time. Only concern is, it may or may not screw up a finish. Build a box, and fixture, use clamps and wedges. Lots of ideas on the WEB.