No Mac support. One could try using this on something like Mac BootCamp?
There are a variety of USB bootloaders out there, but we went with Microchip's stock bootloader due to wide compatability with Windows. Unfortunately their flashing software only comes in the Windows flavor.
There are a variety of freeware bootloaders we chose not to go with, and most of those were still either Windows-only or Windows/Linux. I believe UBW32 is the only one with a Mac interface software released.
Sorry Mac guys! It's been this way for the last 9 years on every one of my hobby projects, I just never support Mac. Not that Mac isn't a fine product, but most of my customers are usually Dell owners. Economically it's not worth the extra trouble developing Mac compatability for the extra 2 sales a month I would receive.