In the late 90s (including 2000) he appeared in JLA (issues 10-15, from 1997, and 38, from 2000) and Martian Manhunter (4, 6 (1999), 13-16 (2000)).
I don't know of anything for the MID-90s, though I suspect the JLA or MM issues are the ones btravage is thinking of, and just misremembered the dates by a couple years - I'd done the same before looking them up. (I'd just known he appeared in JLA and MM.)
He also apparently appeared in a 2002 issue of JSA, which I would have read, but have completely forgotten, and I also forgot his tiny cameo (appearing in a single splash page) in a Superman/Batman arc - where all the extra-terrestrials on Earth got mind-controlled - until just now.