If you know how, it's pretty easy. You do still need to know someone with Windows, though.
1. Download Samsung Magician v. 4.
2. Install it on some windows machine.
3. In the C:\Programs\Samsung Magician\Samsung DOS Application/CDSolution folder (roughly), you will find two iso files. You need these.
4. Install Unetbootin.
5. Use unetbootin to choose one of the iso files (dsrd for firmware updates) copy the files to your usb stick, including firmware files.
6. Boot using the stick. Done.
Note that - at least for me - the Magician software wouldn't install under Wine. I wish Samsung would just upload these images or a USB image at some point...
I TAKE NO WARRANTY WHATSOEVER. Whatever you do, this might break your computer and your SSD. Firmware updates are always dangerous!