[dartho]

First, you need 2 styles installed on your system and you need either 2 domain names or a domain and sub-domain parked on the same webspace.

This hack will parse the URL visited and assign a style based on this information.

Eg:
You have the default style and a "red" style install.
You have the domain "domain.com" and a sub domain "red.domain.com"
You could then use this hack to force the "red" style on visitors to "red.domain.com"

Clear as mud?