i have a thinkpad edge and i think some of the buttons are redundant for my use

here is a picture of what it looks like:
http://blog.couponalbum.com/images/2...20s-laptop.jpg

so there is...
normal tap: left click
two finger tap: right click
press down on touchpad: left click
press down on bottom right: right click (doesn't work in ubuntu for some reason... works on windows and the live cd. currently acts aas a left click
the three buttons above the trackpad: left click, middle click, right click


so on compiz it has multiple options for mouse buttons (7+), i was wondering if i could edit it so that for example pressing down on my trackpad elicits button 8 instead of button 1, while keeping my normal tap?

if anyone could help me with this it would be AMAZING. thanks