WIX 3.5 works using IIS6 for adding wildcard but for IIS7/7.5 there are 2 problems.
Handler Mappings is disabled by default
Wildcard mapping is not added using the IISWixExtension library.
The user will have no idea how to do the above. Yes, very non-technical people.
Cheers
Solved this by updating the web.config file with the appropriate tags that the UI will recognise. EASY!!