Steam's got a support page that explains how to move it:
https://support.steampowered.com/kb_...7418-YUBN-8129
It's not the most user-friendly process in the world, but from what I've heard, it works pretty well. (Note that it explains the process for moving your entire Steam library, but if you follow the steps for setting up a new steam library, you can just reinstall FHM3 there and not have to move everything else to your SSD.)