Ok, this fine saturday afternoon both the wife and the baby where asleep (and I wasn't, a minor miracle

) so I gave it a try.
http://mp3upload.ca/files/12947/advent
(click on "Listen" to stream it without downloading)
I hope you'll forgive my poor intonation (keeping good fretless skills requires constant practice, which requires a lot of time, which I sure as hell don't have), but the idea is there.
I will then stand by my claim that it's easy (since I can play a passable version of it after ten minutes, and I hadn't touched the bass in several months), and also I'll go further and say that there's not a lot of complexity involved there - walking up and down a few notes from a scale.
It still does, however, sound cool