I've been looking for these for a while, and I stumbled across these links recently.

http://rapidshare.com/files/122632086/TonyHawk_sProSkater4Soundtrack.rar

http://rapidshare.com/users/ITC0L7

these are not my uploads, so if they go down, I can't do anything about them. ( I've downloaded them myself, but I'm only keeping the songs I like.)