SmoothMouse is the standard way to do away with the default mouse acceleration behavior imposed by the operating system.
Synergy has several issues when attempting OS X <--> Windows 7 interoperation, and so far the least flaky of the setups is to have OS X be the server. For example, something about my system makes it so that iTerm2 (where all my work happens) basically can't be controlled through the Synergy client. Oops.
Anyway, in order to use Synergy we have to switch off Smoothmouse in order to not gain massive mouse acceleration gain whenever a button is held down.
The only working solution I have found so far is this method to essentially grab an executable file from an unknown author over a plaintext internet protocol:
curl -O http://ktwit.net/code/killmouseaccel; chmod +x killmouseaccel; ./killmouseaccel mouse
I did bite the bullet and ran it after I opened up the executable and saw that it's rather small (which means... absolutely nothing), so I am probably not being hacked right now. Probably.
So my question is basically, surely there is a superior method to tweak our mouse acceleration on OSX? Maybe we can try to find out how this program works and build an open-source version of it so that we don't have to literally roll the dice every time?