Update Manager Rollback

I have VUM 6 installed in my enviornment at present but i need to upgrade a few hosts from ESX 5.5 u2 to 5.5 u3 before going to ESX 6. As you cant use the ESX 5.5 iso's with VUM 6, is it possible to either rollback VUM from 6 to 5.5 or else have two seperate VUM vm's running?

If there were two VUM vm's could i power off VUM 6 while upgrading the ESX 5.5 hosts and then power it back on after?

Thanks!