How to create XEN VM from scratch with xenserver-iso ?

[uzhinskiy]

Please, can anybody provide me and/or explain to me a complete way to create XEN-VM from scratch with packer & xenserver-iso in the following case:
We have a xen-pool with 2 nodes, where is no preferred master-node, and we have a specially created machine(PWH) for working with packer.
We wish run packer with customised configs( CPU, memory, disk, name) for gets fully working VM in this pool.
At this moment we have vm_name.xva file on PWH and nothing about new VM on XEN-nodes. How to export this XVA-file from PWH to our xen-pool via packer?