Nobody will, or should, help you.
Copying games is* illegal, Pirating them is even more illegal!
Backing up software unless otherwise stated goes against the EULA so it is illegal.
I don't know about the process of flashing a 360 drive but wouldn't modifying code to play potentially pirated software also be illegal?
There's also no reason to do this. The xbox 360 allows you to backup games to your hard drive, you only need the original disc in the drive.
Which is exactly why you may want to back up your games, to prevent scratching or losing them.
First off, copying games is perfectly legal. You're aloud to make backups of your own games however many times you please. Pirating games, on the other hand, is illegal. Also, what's wrong with helping the OP flash his 360? There's nothing wrong with that at all, just voids the warranty. He is doing nothing illegal by flashing his 360.
To the OP: I'm almost positive it's not possible to flash it using a Mac, but I suggest using a friend's PC with SATA controllers to flash, it's pretty simple.