You may want to call and check with Outlaw on what version of the firmware is currently installed on units when they ship (they generally ship with whatever the latest version was when they left the factory).

Assuming you can't use Boot Camp or some other method of emulating Windows on your Mac, the best bet would be to borrow a PC laptop (or desktop, although a laptop's more convenient) from someone to install the firmware. It doesn't need to be anything new or powerful, just something with a serial port and Windows installed. Heck, let us know where you are and there may even be a gunslinger nearby who could lend a hand.