I want to programatically create a Books invoice directly from a Deal.

My Deal data includes a multi-line subform which is Lookup into the Product table in Books.

So the invoice would collect Account, Contact, etc, and iterate through subform and create a line item in the invoice.   This is how it would happen if it was done manually. 

I prefer not go through the multi-step process creating a Sales Order, then Converting it to an invoice, because an intermediate Quote and/or Sales Order is almost always irrelevant in my business.

Anybody have deluge code to create Books invoice directly from data in a Deal?