Mapping a key for speeding up emulation in an NES emulator

[Cyath]

Hi everyone, this is my first post here. I was wondering if anyone had any idea of how to map a key for frameskipping or emulation speed to the keyboard (or gamepad) for an NES emulator? I am looking for something similar to VBA's interface.

I've used Nestopia, RockNES and FCE Ultra as well as having read their documentation, but I can't seem to find a way to do what I'm trying to do. A friend says that the "~" key in FCE Ultra is the way, but I tried that and no go.

Can anyone help?

[Bodomi]

In Nestopia, you can fast-forward with the "tab" key.

I just tried "~" with FCE Ultra, worked for me. (Or in my keyboard, it's "§" key, left from "1" key.)

[BIrvine]

For other emus you might want this on, there is usually an option for 'speed' when in key setup, although every emulator is different.