Your instructions were fine freemangordon.

My problem was not being able to reinstall libbridge2 because I didn't have the fremantle/ssu/002 repository enabled. The apt-get error suggested that libbridge2 was non-downloadable, so rather than fix my repos I tried playing with bridgedriver.ko and the /lib/dsp files.

I likely wouldn't have figured this out without my brand-new spare N900

Anyways, I now have libbridge2 reinstalled, the proper bridgedriver.ko, and the proper /lib/dsp files in place, so everything is fine -- hopefully!