If you're using a form, clamp the bow at the handle and work your way from fades out to the tips using dry heat. Like already mentioned, heat one area 6-8" and then clamp it (using shims) and move on to the next area. You can remove deflex, propellor, and add reflex all at the same time using a form with dry heat.
Like Pat said, having it floor tillered helps the tweaking process because of less wood to heat. I usually only use oil on the belly and edges of the limbs and leave it off the back. Just cuts down later on the sandpaper clogging up with the oil when finishing. Sometimes I don't even use oil with osage since it has natural oils in it...just have to keep an eye on the wood when heating it. Almost always use oil on white woods though.