Looking for MouseFix?
MouseFix 1.0 was originally developed by Richard Bentley to reduce the effects of mouse acceleration under Mac OS X, and was subsequently tweaked (through ye olde trial-and-error) by me to produce MouseFix 1.1 back in 2006. It was originally developed for OS X 10.4 “Tiger”, but it apparently works with OS X 10.5 “Leopard” too.
Unfortunately the original site (Google cache) seems to have gone walkabout at time of writing, so I’m re-uploading version 1.1 here.
I’m afraid I don’t have copies of 1.0 or 1.2, but: Here you will find “1.2.1″ by Allen “Chip” Parker which apparently runs on OS X 10.6 “Snow Leopard” (not sure about backwards-compatibility) and is based on MouseFix 1.2.
The only other (free) option that I’m aware of is to install a 3rd party mouse driver, such as Microsoft’s Intellimouse. I believe Logitech also have an OS X driver which can disable mouse acceleration, but I’m not 100% sure. I have used Intellimouse on my own Mac (with a Microsoft USB mouse) and can vouch for it, although it’s hardly an ideal solution. Truth be told, while MouseFix does a pretty good job, at present I think a 3rd party driver is about the only way to 100% defeat mouse acceleration under OS X. Most unfortunately. Why it isn’t just an option in the OS (even if it were only for external/3rd party mice) I have NO IDEA.