Need help modifying code to make FastForward behave as a toggle

[TheManuel]

I'm pretty sure there is no setting to make MAME's FFWD functionality work as a toggle instead of having to hold down the key, without recompiling the code.

Could somebody tell me what I would need to change in the code to make this happen?

Notice that I'm referring to FFWD not throttle, which does behave as a toggle.

Thanks in advance.

[TheManuel]

I ended up using AHK to implement the toggle functionality when pressing the FFWD key. Luckily, no messing around with the code and custom builds were needed.