Powerpoint on a mac

I am trying to run a slideshow with a remote controller on the data projector. I am using Powerpoint for Mac X. I am running Mac OS X. I want to go to a previous slide during the show, and using the remote I hit the "right click" button, which works when the slideshow is driven by an XP machine. When I click the "right click" button on the remote during a slide show, I get a menu on the slideshow that lists the following options: help, next, previous, go, etc. I want the slideshow to immediately go to the previous slide and I don't know how/where to set it to do so. Any ideas?
Thanks,
dig