Hi,
The general issue here is that vSphere Replication does not have public API. Thus anything related to vSphere Replicaiton operations won't be possible through powerCLI. In specific, disable/enable replication for VM.
The rest of the steps you can automate using the guidence from here http://www.yellow-bricks.com/2012/09/21/can-i-protect-my-vcenter-server-with-vsphere-replication/
As for disable management you could probably think of some tricks with the networking on the target vSphere Replication server. Unfortunately I'm not sure this will be supported.