Here is a demo flash movie of the gameplay so you can get an idea:
I am making a side scrolling game that uses hand draw backgrounds (drawn by me) with invisible boxes for the floor that have physics applied. There smooth sloping inclines. The invisible boxes are set to immovable. The floor does not vary that much in angle and the angles are slight.
I have a beetle type enemy that I need to 'slide' (walk back and forth) across the floor but not roll or cartwheel. There are no other objects with physics in the games besides the beetle and the floor. So far everything is working good and the beetle walks great and rotates with the scenery as he walks but every once in a while he "trips" and cartwheels rotating too far (This happens far more often in Firefox for some reason). This would be easily remedied if I could limit the rotation of an obj using physics. I have looked into ragdoll a lot an cant get that to help.
The beetle using the following behaviors:
Platform (ignores default controls)
This works best I have found... but does not account for the tripping
The only reason I didnt want to share my CAPX is because I have images that took months to draw in there that I am being stash with at this point.
There are screenshots of my game on kinglith.deviantart.com (Luna)