Blocking weblinks in MSN/Live Messenger from central point

Hey all.
I was wondering if any of you know a way to block for weblinks in
MSN/live
messenger from a central point.
My boss wants to allow msn to be used while at work, but i still want to
control some of the major risk, like no file sharing and no weblinks in
the
chat window.
The file sharing was easy taken cared of, but for the like of my i cant
seem
to find a way to disable web links. I know of course you can set it
manual
on each machine, but this isn't a valid solution.
I've look around in the registry to see if i could find anything useful,
and
i found:
HKEY_CURRENT_USER\Software\Microsoft\MSNMessenger\PerPassportSettings\Us
er
specific number\UserSecurityFlags
But the problem is that each passport account has their own user
specific
number.
To put it simple, is there any to control weblinks in messenge with a
GPO or
something like that.

/best regards
Mads