The previews folder has to reside in the same folder as the catalog.
So you would need to move the whole Lightroom folder to the other drive.
Lightroom will probably be a little faster if the folder is on an SSD, but I'll leave it to others to comment on that ...
After having moved (I recommend that you copy, and delete from the SSD once you've established that everything works), LR will not find the catalog, so the easiest way to get up and running is to double-click the catalog file.
Actually you would have to move the whole Lightroom Catalog Folder along with all the subfolders and files under the main catalog folder. Not the Lightroom Program folder.
Follow-up question to that. Is there a worthwhile advantage to having the catalog and previews on an SSD as opposed to an HDD?
As far as I know, you should get a performance boost by putting the catalog and previews on an SSD (but not if you put the original photos on an SSD)
Yes, you can put the previews on a separate HD using Symbolic Links (and leaving the catalog file where it is). See How to move Previews from SSD to HDD | Lightroom Forums