hey, with BetterTouchTool you can set custom gestures for those swipes!
If you want to set a shortcut for 3 finger swipe an expose you have to deactivate expose while entering the shortcut in BTT. (Go to system preferences => keyboard => expose. There set a custom shortcut but do not activate it yet. Then set the shortcut in BTT and activate it in the system preferences)
Oh yeah, I have that down and it works beautifully. However, notice that an opposite swipe on the trackpad will "close" expose if it is still open. For some reason it is very natural to swipe down to open expose, and back up to close it.