I don't know for sure about the fifth button, but you should be able to get the wheel working with ZAxisMapping. Add this to your mouse section of your XF86Config:
Option "ZAxisMapping" "4 5"
To get more buttons, the option is something like ButtonCount, but I don't know for sure, and I don't know how to make that button do anything. Try the XFree manual: http://www.xfree86.org/4.3.0/
Edit: from browsing the XFree manual, I think the ButtonCount option is:
Option "Buttons" "6"