There are several things you can do in Photoshop.
The warp tool is fun and easy. Do a transform, warp. You can push the paper around like putty. To curl the edge, just grab a corner control point and peel it back like the paper is curling... like the edge of a sticky. You still need to dodge and burn or something for the shadows, but you'll get the right shape.
Liquify filter gives you similar control. To make the liquify filter a little more friendly and not use so much memory, make a selection around the area you want to work on, then choose the filter.
I'm not exactly clear on what you are doing, but if you have a pencil under something, you can also do a displacement map to make the paper look "bumped" out. That process is little more complicated. I did a quick search and there are several tuts out there - I don't know how good they are, but search on how to do a displacement map in photoshop.
Good Luck!
