I've made a macro to cast Soul Swap Exhale on my mouse-over target, and it works fine if i press the action bar button, but I'd like to map it to my mouse button 4. I've tried the keybinding tab on the escape menu, but WoW doesn't seem to recognize Mouse Button 4 or 5. Right now mouse button 5 is just set to auto run, and I have no idea how to change that.