There are a couple of ways with the HVX to get slow motion without rendering, one shooting with the variable framerate in either 24p or 30p which does the pulldown in the camera. The other is to shoot in 60p and use the FCP frame rate convertor to remove the extra frames and then drop the converted clip into a 29.97 (which I did here) or 23.98 timeline. Still working with that original footage I shot but I've learned a few new things about cam setup which should hopefully give me more of the look I'm after so hopefully I'll get another chance to shoot Chris soon.
Anyway check it out. I'll have to do a test rendering the 60 fps file to 50% speed in FCP and see how that compares. Not sure it will look any different compressed down this much.
http://homepage.mac.com/rd4tile/FileSharing7.html