Initially it worked (for, like, a minute) just by using the mouse controls in the Options menu, but after that I just went to mouse_def.xml and C&P'd the text Caarie gave, and it's worked just fine.
I tried to find mouse_def.xml but I can't find it anywhere. All I have in my planeshift folder is:
Art, Data, Docs, Guide, psclient, psclient.cfg, pssetup, pssetup.cfg psupdater, readme-osx, support, uninstall, updaterinfo,xml, vfs.cfg
Any ideas where it could be? Thanks.