Ripping a 4.1 Host into a new 5.5 Cluster WITHOUT access to the 4.1 vCenter Server

I have a customer that has his 2 vSphere 4.1 hosts in a vCenter 4.1 cluster that is NOT under his control or access. vCenter server access is with a 3rd party he is nervous about his account being taken over by a new provider. I am looking for the safest method (preferable non-disruptive) to import these 2 hosts into a brand new vSphere 5.5 cluster with 2 new hosts and vCenter 5.5 server. He does have access to the individual hosts through the vSphere Client as well as his local NAS based storage where the VM's reside. The end result is to vMotion and Storage vMotion the VM's onto the new hosts and new storage non-disruptively then retire the old hosts.