'Toggle' Mouse button

[Ernie]

Feel free to move this Mr Moderator.

I've searched the web, but can't find how to 'toggle' the thumb button on my mouse, so 1 press and 'shift' is on, click it again and shift is off.

Any ideas, where I can look or find out?

Many thanks.

 

[Ernie]

Lol - omg I just realised how stupid it sounds, because it is the equivalent of CAPS LOCK, but its for a games addon, which requires you to depress shift or cntrl in syn with another key, so CAPS LOCK won't work, because it's not an option on the addon, I suppose because CAPS LOCK is kind of a passive key stroke.