Automatic Configuring

I am currently researching the process to migrate users from Exchange IM to
LCS 2005.

I have the migration documentation, and can get the contact lists exported
and imported into the new server, but I have 1 issue I cannot find a
resolution to.

How can you automatically force the clients to SIP communications and turn
off the Exchange account information in Windows Messenger. I don't see it
in the group policy, and the only way I can figure out how to do it is to
manually make the changes at the client.

Is there a way to automate the process.

Any assistance is appreciated.