How do I load .sav files onto cart/back up files onto computer (os x)?

Hi, I've just recently started using LSDJ on an EMS 64m Flash cart through a CBG. I now have a few songs I'd like to back up on my computer as well as some .sav files I'd like to load onto my cart (courtesy of Danimal Cannon), the thing I am having difficulty on is how do I connect the cart to my computer first of all? (I'm using mac os, which is proving to be difficult to find a good backup software for) and also after I manage to do that, how would I transfer files between the two and such?