I think he was looking for a full backup of his BB using his Mac, like DM for Windows does. Aside from getting a windows machine, the only thing you can do is:

If you are running Leopard, use Mac boot camp program and set up your Mac to dual boot to both Mac and Windows [you will unfortunately need to buy a copy of Windows]

Buy a program called Parallels. This program allows you to run Windows inside of your Mac OSX. You would need to buy a copy of Windows for this as well.

Until RIM realizes that not everyone uses Windows and puts out their Mac version of DM that they have been promising, then this is basically all you can do to get the same level of backup that Windows users get.