[themes] optional css configurable by visitors

hello.

this was posted at the drupal forms but got no reply, so I am trying my luck here. I have found this page that explains how to have an optional css file configurable by visitors. http://drupal.org/node/59895

since I want users to choose between high-contrast and normal colors, I am very much keen on getting it to work. I have tried it on my website but it didn't work for some reason. may be there's something I am not getting? or may be some typo that I couldn't figure out?

has anybody been able to get it to work? if so any examples? and, if not, do you know of a similar hack that would produce similar results? any help, as ever, will be highly appreciated.

Regards, Mohammed al-shar'