When I had gargraves, I had success bending it on a 55 gallon drum....also used the belly method.....since I was well equipped..
Here's to Genesee Beer! If you're ever in downtown Rochester, NY, the brewery has a great restaurant and gift shop to buy beer/stuff. We were just there a few months ago. Awesome beer in a variety of flavors.
Few notes on GG to share (my 2 cents):
I made a jig for GG. I found it was better to make the radius a little smaller than you want because the track flexes back a little. You just have to play with it a bit and use wood blocks to work the bends. Also clamps, as someone suggested, help as you're bending. GGs the company told me that, yes, WD40 is good for used track -- had the same issue with some used I bought. I also used some gargraves factory made curves halfway through my project and, to be honest, I wish I had used more of them instead of all the time I spent trying to roll my own. They make REALLY nice curves with metal supports to keep the shapes. You pay more, but...
Sorry, I canm't remember who posted this.
Here is some additional info on how this man curved his track.