While I haven't made this repair, I have been involved in craft work most of my life. Here are my thoughts on the matter:
I would probably choose a black silicone adhesive.
I would require a very small "spatula like" tool with which to apply the glue. I have several, but if I had to, I'd flatten the end of a nail and file it to shape to get the size tool I needed.
I would experiment with the following for "practice"
- I would heat the tolex to be glued to see if it relaxes it enough to eliminate the curl as much as possible. I'd try a hair dryer first.
- I would apply a small drop of glue on a test item...as little as possible to make the repair.
- I would let it dry for a minute or so to get a feel for how long it takes to set up and how long my working time will be.
- After it has set up, ever so slightly, I'd lightly tap it with a scotchbright yellow plastic scrubber to simulate the texture of the tolex.
After you have done this on some scrap anything, you will then have a game plan to make a professional repair. Not difficult, just a little more time consuming. Also, I have made scuffs on my amps "disappear" with just a little black shoe polish, carefully buffing it until no more polish will come off on a dry cloth or paper towel.
Just my :2cents: