MS IM Group Policy

My boss wants me to set up our network users' to a standard for IM
enterprise-wide. I figure I need to do it via Group Policy, but I'm not
sure what registry settings, etc, need to be set: Configure all IM
clients to automatically login on Windows boot and to launch when a VPN
connection is established. Individual preferences should be "locked"
system-wide. Also, remove preference to show when a user has logged-in.

I know this is the opposite problem from most of you, I know it's
usually the opposite... But can anyone help?
--
Stephen Wright, MCSE 2K, MCSA 2K3
Service Engineer
LOGOS Communications, Inc