How to ask for user selection and pass result from Xrm.Utility.lookupObjects to Custom workflow as an input parameter

I need to create an On demand workflow that runs on selected records in a view, that

1)initializes Xrm.Utility.lookupObjects so user can select a single lookup from a different entity

2)Passes this user selection as an input parameter to the workflow. 

3) The workflow simply adds this selection as an additional field for creation of similar records in another entity.

Really basically copying the selected records(less a few fields) and then adding the user selected field from a different entity to create new records in a different entity.

Any ideas appreciated. Its the user interface selection that has me stumped. Have researched combinations of actions, html, etc.. nothing coming together.