Syntax highlighting in Xcode isn't working so well with Xcode 4. TextMate and Sublime Text 2 are the more popular environment for Cappuccino editing right now, I think, while using Xcode only to edit the UI files.
The Interface Builder integration is fantastic now. You really should be using it, it's worth the time it might take to port your CIBs to XIBs. Lots of things just work for Cappuccino in IB, including bindings and custom table cells.