You can map the tilde and back tic to different keys without software using the Poker II's built-in programming layer. However, in order to access those functions, you need to hit the "Pn" + key to access it. It's certainly better than holding Fn + Shift + Esc to get a tilde, but it's probably not exactly what you were looking for.
Edit: As mentioned you can map tic and tilde to the right control key, and this is done by flipping one of the dip switches. Another dip switch changes the left Windows key to another Fn key, which is useful since KBC moved the arrow keys to WASD. I use my Poker II with a Mac as well, and it works great. Since I "locked out" what would be the command key in OS X, I used system preferences to map that key to control and the actual control key to caps lock. There's only one program where I use control so it took virtually zero adjustment time.