Invoices instead of Sales Receipts

How might I go about switching to importing Invoices instead of Sales Receipts?

I can code the invoice system, as it doesn't appear to be written into uc_qb yet.

I believe this is the XML required: http://www.consolibyte.com/wiki/doku.php/quickbooks_qbxml_invoiceadd

Do I need to somehow tell QuickBooks to request an invoice instead of a Sales Receipt, or is this handled from within the uc_qb module code?

If you don't know what I mean, please ask for clarification. It's urgent, and I'm unsure of how best to implement it.