Dimension Set ID in RapidStart

My customer wants to import Vendor Invoices on a weekly basis. These invoices can have quite a number of lines and typically the difference between the lines are dimensions for certain criteria. The best way to do this with standard NAV functionality is to use RapidStart. The issue I have is that it is not possible to add shortcut dimensions to the import because the Dimension Set ID field replace the entering of dimensions on the import. Does anyone know if there is a way around this to be able to record these dimensions other than manually entering on the purchase document? Another possibility would be to use the standard purchase code however this means manual creation of purchase documents.

I would appreciate any ideas.