Richard,

I have the same sort of requirement for my modules -- I need the user to populate the module with "settings" prior to use.  Here is what I do -- may not be the "dnn" way:

1) On page load I check to see if an expected module setting exists in the module setting collection.  If not the I declare the module as "new'
2) If a new module then I post a message requesting the user to go to the module settings page and complete the information.
3) On the settings page, if this is a new module (checked again a page load), I populate my settings with defaults then render the settings page.
4) Once the settings are updated, the expected module settings are placed into the module settings table.
5) When control return to the module, the expected module settings exist and the module is allowed to operate based on those settings.

I use my own settings page -- I typically do not use the integrated module setting that is part of the "Settings" on the module menu.  This means I must add an action item for my own setting page, plus create a explicit page in the module configuration with a value other than "Settings" -- I use "EditSettings"  for a key to my Settings page.

I create a Settings Class that contains all of the values placed in the Module Settings. I also have a Settings Controller that will read or persist the my settings.  One of the controller's properties is "IsNew" and in this property I will check for a Setting Value(s) and if the value is not found will return true.   If the IsNew method returned true, I can apply the default values to the module.

Hope this help
Paul.