Wikiwide, you are a star!

I did not find that post before, was probably searched for the wrong keywords.

EDIT:
Still not entirely perfect as (if I understand it correctly) all I can do with it is customize the pre-existing alarm tones, which is what I can do by simply replacing the relevant sound files in /usr/share/sounds/. But at least I get the idea that it is not as simple as ringtones. Pity.