I was wondering is there any way to add additional, alternative key binding to a particular feature in compiz? 

I am using Wall plugin and on my ThinkPad it is convenient to switch between horizontal workspaces with media buttons for browser navigation. But there just two of them, so I have to use completely different combinations to switch between workspaces vertically and that would very helpful if I can also use similar kind of combination to switch horizontally as well *in addition* to those media buttons.

Is there a way maybe to send a message to the compiz to execute particular command? That would solve the issue.