This video explains steps involved in a PowerCenter domain migration from a host A to a host B and there is a sitekey in place. For instance, like in PowerCenter 10.1.
How to find in which host the Repository Integration service is running in a multi node domain
How to unassign services from an expired key and assign them to a valid key in 9.1.0 and 9.5.1
Converting and adding of a self signed certificate to use a Webservice Consumer transformation