Concepts Unlimited (CU) works fine, though it lacks the MCAD
functionality that Pro/E is noted for. CU is marketed as an Industrial
Design package, and has fairly extensive surface and rendering
capabilities. The company also has lower cost packages that are solids
read only, great for drafting or artwork.
http://www.csi-concepts.com/
They have a demo version that you can try, very easy to learn, and I can
bring CU files into Pro/E (WF3 030) easily via IGES.
You might sign up for the forums there and post more specific questions.
Pro/Concept will run under OSX, but it wasn't really developed for editing
Pro/E files as much as acting as a standalone Industrial Design front end.