Just to freshen up the information here, having just grappled with this: As of OS X 10.8.2 SetFile is still no longer included in a regular base install (to the best of my knowledge). I have read that as of 10.4.X it could have been found under
It also now seems that xcode no longer installs its resources into the root directory
/Developer/ but instead keeps all its resources within itself, i.e. with in the package contents (right-click → Show Package Contents). I can't give the path at the moment as I'm not on a 10.8 box, but it didn't take me long to find it once I was in there.
If there is a method that supersedes SetFile which doesn't require dependances outside of a base install, I'd sure like to know about it!