check the workflow "Create vmfs for all available disks" in Library / vCenter / Storage.
It contains some example logic how to create VMFS datastores, you should be able to adopt it for individual volumes.
Also, check out ONYX or Onyx for WebClient Onyx for the Web Client to figure out the needed API calls when you create them manually in the client.
I did not see that workflow. I'll take a look.