For this I typically do the bevel in either C4D or Lightwave and then go back into Carrara. I think there's also a plug-in from zaxwerks that can do something similar right inside After Effects (which now can operate in 3D mode). Carrara can do bevelling on text and I think there was a discussion a while back about turning a piece of vector art into a character in a font and then using the text bevelling capablities of C. There are zillions of dingbat-style fonts now so the text method is at least a useful backdoor approach for certains kinds of shapes.