EVER heard of booting from an ISO disk? Its how I updated my Crucial M4 and its how I can update my Samsung 840.
Sure, to do it from within an OS, you need windows but its very very easy to boot from .ISO DVD and update. Literally no Windows needed.
**EDIT** I just tried it and it actually didn't work(emphasis mine), at least on the first try but this is typically not the case. Usually an .ISO file will let you update the firmware on any machine for SSD's.
I do know what an ISO is, had a 128 GB Samsung 830, tried to update it and could not. I returned it and got a Crucial M4. Updates like a champ from an ISO image on a CD.
It seems Samsung's
answer to this exact question is you need a Windows Computer to make a bootable USB and "may" be able to boot from said USB. Many have friends using Windows. A CD would probably work too.
From searching MacRumors you can see many have had this question and end up using a) booting into a Bootcamp version of Windows on your machine, or b) installing the SSD inside another Windows machine. That's right, inside, not in an external USB drive because the firmware utility see's the USB controller not the SSD.
Also, shortcut3d said this about other drives:
"..
.it seems I've had no problems with OWC or OCZ current Linux boot disk methods to update the firmware. I can confirm that you can update the firmware over Thunderbolt as well which is good news because you can put any Thunderbolt Mac in target disk mode and update from another Mac with bootcamp. No need to have bootcamp on each machine.
I would not try running a firmware update through a VM. The complete path through to the SATA controller is virtualized. This will most likely result in bricking your SSD, if the tool even starts. Good tools will recognize this and prevent the user from updating the firmware. "