I am not sure if you can sort the #@ alphabetically because when you join a channel. That channel goes at the beginning of raw 319.
For example, you're in @#Help and @#Services. Then you join #mIRC.
Now it would look like @#mIRC #@Help #@Services.
Though I could be wrong, it
might be scriptable but what would I know.
(Edited post as I had a UBB code error.)