Hello,
I'm not following where you may be having the issue.
If you're having an issue setting the DVPortgroup, check out this thread:
http://communities.vmware.com/message/1731492#1731492
If you're having an issue with the customization, have a look at this provided workflow:
"Clone, Windows with single NIC and credential"
PS - Most likely, a workflow should only perform 1 OS Customization. I can't think of a reason you would want or need to do more 