If you have a full version of Photoshop, you'll have to use the bezier tool.
Thing that produces lines like this:
http://tavmjong.free.fr/INKSCAPE/MANUAL/images/PATHS/BezierTool3.png
There's really not a "easy cheat" method for clipping things out. You simply need to trace it out with smooth curves, and maybe even offset (well, in-set) the path to make sure you don't have any stuff you don't want in your clipped object. You can also duplicate the layer and use a small eraser tool to erase out the part you don't need, but that's more work and more tedious. I guess you could try the "magic lasso" tool, but that always provides crap results too, unless it's shot on a solid background like white, or a green screen.
I work in Photoshop daily, and I really, really wish there was an easier way. But if you use any other method, you'll wind up with bad, square pixel artifacts around the edges. I think eventually they'll get a better method, but for now, that seems to work the best for me.