That's right, 5 buttons. Make sure your
Option "buttons" "5"
line reflects this. Also, yes, XF86Config-4 is the file you should be editing.
Pitoe, the settings should be the same under any linux distro (and even *bsd). So if the settings worked in one distro, copy them to another and all should be well. If it doesn't work then it's not your xfree86 setup it's you distro set up. Maybe you haven't loaded an appropriate module. Maybe the right support hasn't been compiled into the kernel.