How to Kerberize an application

[prp@ALUMNI.CALTECH.EDU]

I'm looking for a tutorial (ideally) that would describe how to modify an existing service, at the point where connection is made to its listener by a prospective client, to support the Kerberos protocol. In fact it would describe how both client and server must prepare their respective portions of the dialogue, or condition the states of their processes, with references to appropriate GSS-API or Kerberos API calls.