Hoom... yes. The reason I need this word is when specifying how a list of items can presented by a system - for example a list of members of an organisation on a website. I'm trying to avoid saying "You can also view the list in reverse alphabetical order". The same problem comes up when trying to list date-based items like a list of events - that can be list in chronological or reverse chronological order.

Omegapsical is pretty decent.

The only advantage to zalphabetical is that is suggests what it is quite well - dumb people might more easily understand what it means than omegabetical...

Anyhow - thanks for the suggestions.