I have used block erupters on my Mac Pro, but only with Bitminter software (Java based), they worked fine.

I have had lots of problems with other software, but got most stuff working eventually, using a PC version AMD 5770 card for GPU mining.

I havent tried any other software with my erupters (they are running on a Raspberry Pi to save electric costs) but I believe they would work ok on the Mac with the latest version of CGminer.

Phil.

edit:  You need to install a USB driver, the link is here on Bitcointalk somewhere (its a Silabs UART driver?)