Workflow to Automate Host prefix of VMs In vCloud

hi all,

We have vCloud director 5.1 in our Environment and  unfortunately we don't have vCac to automate the Host Prefix Process ,and we have decided to deploy vCo 5.1 And we have downloaded Custom Vapp Deployment Package and modified to work with host prefix and automatic addition of vApp user to local user group of VM Deployed, but It doesn't  worked  ,please any one with good knowledge on Vco Workflow Help me to achieve this ,i have attached  the Workflow for the Reference.

Thanks In advance,

Vasanth.S