Two cheesy solutions:
1) Sort one temp-table into another multiple times until you have "boiled down" the sort you need.
2)Output your fields into a text file with keys and rowid, then use unix sort and load that back in.
(replace rowid with recid and temp-table with workfile if necessary, I don't remember if these both existed in version 8!)
I am ashamed to admit I used #2 many years ago and it was faster than I would have guessed.