There are several questions around how to allow a self-hosted WCF application to use BasicHttpBinding with HTTP.SYS without requiring administrative privileges. It boils do
I have exactly this problem in my bug list but it has currently low priority so I didn't deal with it yet. Anyway we found this tool (download the source) which uses mentioned function and it has all needed code to work (it is long way from having Win32 function and having working solution).
The Win32 API to use is HttpSetServiceConfiguration.