TBH, I just place it on the floor and put the pedals on it. I use a pretty big piece, enough to place all of them on it. But I would imagine some kind of rubber glue would work, if you don't mind messing up the pedal (and maybe making disassembly for repair harder).

In fact, I've got a variety of different sizes cut, for different pedal needs.

If you kick the pedal, it won't stop it flying, but under normal use, it pretty much stops pedal creep dead in its tracks!