Easiest thing to do is download the
d20 Modern SRD, and use the Allegiances rules as a replacement. That allows you to keep some of the basics, while being much more flexible.
To summarize: each player/critter gets three allegiances. This can be something as vague as 'Good', 'Chaos', 'Charity'; or as specific as 'The Company', 'Her Children', 'The Code of Chivalry of St. Bartholomew VII' (yes, I made that one up.

).
With that, you get creature entries like the gnoll, which typically has allegiances to Chaos and Evil. If you want a gnoll who really got into the hippy movement in the 60's tho, he could have allegiances to Chaos, Free Love and Peace instead.
(On a side note, now I have this image in my head of a big, burly gnoll in a tie-die shirt with John Lennon glasses on, smoking a joint with a big grin on its muzzle.

)