Is there a way to some how automatise Mac OS X to change the Etiquette color of a folder, regrding is modify date ?

I am thinking of my Client folder. In it, I want to have colored in Grey when a folder is older than 30 days (like when a project gets inactive).

any tips for this ? maybe doable with automator or apple script (which I don't know and haven't find anything on the web yet)

(i use mac os x 10.6)