Howto disable Wlan with GPO when in a connected domain..??

Hi!

I have a little problem I'm working on, and I hope some of you might help me.
We're running a connected domain (no wlan on the inside), and currently we
don't allow users to enable their wlan cards at all.
We'd like to allow the users to enable the wlan cards as long as they're not
connected to the domain, so they can use wlan when they're traveling.
Is there a way to manage this with group policy?
The idea is that once the users connects to the domain via lan cable the
wlan gets disabled..

Any help is appreciated!