There's a very good TechNet article available that describes the steps that are required in order to fail over from a CCR cluster in one site, to an SCR target in another site. It also covers the procedure to fail back once the problem has been resolved.

 

Standby Continuous Replication: Site Resilience with Standby Clustering
http://technet.microsoft.com/en-us/library/bb738150(EXCHG.80).aspx

 

Posted by Chris Stevenson