I have no idea on Mac's. I use WinRar to extract the files. Anything that will open a .rar should be able to help you. I am not Macsavvy so I couldn't help you, maybe someone else here who uses Mac's could.

Bruce's guide starts at 3 because he is in the process of making 1 and 2. It is quite alot of work putting together documentation especially when he has a RL to accompany his gametime.