Works on Snow Leopard as well via winebottler:
http://winebottler.kronenberg.org/
Steps (because it took me a bit to figure it out):
1) Put Wine.app and WineBottler.app in your applications folder
2) download the Eureqa installer for windows
3) double click the Eureqa installer for windows (should open via
WineBottler)
4) complete the install
5) Navigate to ~/Wine\ Files/drive_c/Program\ Files/Eureqa\ Software/
Eureqa/
6) make an alias to Eureqa.exe
7) move that alias to your applications folder and run it