Set default product for multi-product Office 2007 network installation point?

I have a network installation point that includes files for Office Standard,
Office Pro, Project, and Visio (copied the appropriate product.WW and
component.en-US directories from the respective media).

When running Setup, the user gets the choice of which product to install.
This is almost perfect! But, since the products are alphabetized, Office
Professional, which comes first alphabetically, is the default. I want
Office Standard to be the default selected radio button.

- Config.xml at the product directory level doesn't help, since it isn't
read until after the product choice.
- Also, a global Config.xml next to Setup doesn't seem to work, since Setup
doesn't seem to accept more than one Configuration section in Config.xml
(which would be required for more than one product).
- An unattended installation is also not viable, since not everyone is
licensed for Pro, Visio, or Project, so we can't put them there
automatically; the user should be able to choose.

Any ideas on how changing the default choice might be accomplished?
--Michael