How to use XDMCP

I'm running SuSE (9.1 & 10.0) on 3 computers and have noticed that one of the login options is to login to a remote system, using XDMCP. What I can't find, is how to enable it on the remote system. What do I have to change on a SuSE system, to allow remote login. Please don't worry about security. This is being done on a private lan, behind a firewall. tnx jk