As long as you're paying for PS, check out Codeweavers' Crossover Linux. You can run native Windows programs under Linux (Crossover is a tweaked version of Wine).
If I remember the Wine Weekly News report correctly, I think Disney wanted it working on their Linux machines they used for rendering, and committed back all their fixes to Wine. So whatever that version was is probably pretty usable.
It looks like Photoshop isn't quite there yet though: http://www.codeweavers.com/compatibility/browse/cat/?cat_id=...
It is one of the top applications that they are working on: http://www.codeweavers.com/compatibility/toplists/