I installed the Steam Beta on a PC with a 36GB os partition which doesn’t leave much room for games. I spent some time trying to translate windows tutorials to linux before I realized how stupidly simple the solution is.
1. By default, Steam creates a folder in your home directory named Steam. Move this folder to the new location.
mv ~/Steam /mnt/media
2. Create a symlink
ln -s /mnt/media/Steam ~/Steam
If you haven’t heard yet, you don’t have to be invited to participate in the beta.