Don't do it! This is causing several people to experience hard drive wipes!
http://forums.elderscrollsonline.com/discussion/105519/install-wiped-my-hard-drive-contents-with-no-warning
AleriSadasIndoril wrote: »With a small SSD I would be careful, an SSD should not be fuller than 75% as rule of thumb. On a small 128 GB with OS and ESO installed that could be very close, safer it is from 265 GB up.
I have the PTS installed normally on my 265 GB SSD, then I shifted the PTS folder simply to the other HDD and the PTS server is running without problems.