Yep, that (partially) works, thanks!
For the "old" Firewire stack it's sufficient to blacklist ohci1394 (and/or ieee1394, which ohci1394 depends on, if you want). However, you must also run update-initramfs -u after editing the blacklist file, otherwise the settings won't take effect on the next reboot (the modules will automatically be loaded while booting; manual loading after an rmmod will fail as expected, though).
Also, I recommend to also put options ohci1394 phys_dma=0 into the blacklist file in order to force that option to be used should the module ever get loaded (for whatever reason).
I've updated the article with some more info on blacklisting (for the old Firewire stack). No testing done on the new stack yet, so I've omitted that information for now until I have actually been able to test all of that...