Move vCenter to another cluster....how?

We're running the vCenter Appliance 5.5.0 and need to move from a cluster with ESX 4.1.0 hosts to a new cluster running ESXi 5.5.0 hosts.  Both clusters are in the same Datacenter, but no common storage.

We've migrated all VM's from the old cluster to the new one using vMotion.  Now it's time for the vCenter itself.

How should I go about this?  Some downtime for vCenter is probably inevitable.

Thanks....Lyle