Blender displacement mapping, cycles vs blenderrender

Judge Death

Ok I'm working on a project I won't describe as it might offend someone, but Iam trying displace mapp;ing based on image textures. In fact here's what I've been using as a guide: https://www.youtube.com/watch?v=VY9vHdwUo98

Now I have gotten it to where I can use this technique in blender render to create a deformed mech that actually has 3d topology, as a horrendous cost in faces by maxing out the subsurf mod, but when I try to do it in cycles I get something that looks ok in some angles byt is still a flat surfacew with an image on it. Any tips on doing displacement in cycles? If you can just point me to a nice vidtut that'll be sweet.