You've tried "0 */2 * * * command", and it doesn't work?
Have you tried "0 0-22/2 * * * command"?
If neither of those work, then you're stuck with "0 0,2,4,6,8,10,12,14,16,18,20,22 * * * command".
I searched around a bit for AIX man pages. Best reference I could find, though, was the Wikipedia cron
page, and the only reference it had to idiosyncrasies of AIX was not recognizing 7 as a day.
Just as a side comment, if all your hourly things run at minute 0, they're going to bunch up. If the only restriction is just they they run once an hour (or two), pick odd (different) values for the minutes.