You don't actually have to do it from another machine. When I flashed a card years ago I just turned on remote desktop before I installed it, shared the screen and flashed it directly on the Mac.

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(or a Mac if they have a compatible card and ROM

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The problem with that is not all cards can be flashed with the utilities available for Mac OS. I included that, but made a note that it can not always be done. imo it is less hassle to do it on a PC anyway.