CAD/CAM will get you as far as designing your parts and producing the g-code, but if you also want to run the CNC machine with your Mac, you will need a piece of software similar to Mach3 or EMC to run the g-code. There are a few CAM plugins for SketchUp as well, but I've never used them, so I can't vouch for them. Here is a list of a few: I've also read good things about punchCAD: Of course, there is always SketchUp if you are in a pinch.
There are several CAD/CAM programs out there for MacOS.
YOUR CNC SOFTWARE COMPATIBLE WITH MAC? Current Solution
