Changing and remapping inputs for a specific application

[gandalf3]

I found this nice looking 3D modeling program called topmod, However the mouse input to rotate the view is Alt+Left click which is the same as for moving windows around.

This wouldn't be a problem, but the program does not have options for changing the mouse gestures, and I would rather not reassign the alt+click in the DE as I rather like it for moving windows around.
So I was wondering if there was a way to use a different mouse button to send a "alt+click" signal to the program, and still have alt+click drag it as normal?

It should be noted that I'm running Arch, but I don't see how that could make a lot of difference in this case..

Thanks.