Here is an example URL for a simple XML search:
https://HOSTNAME/texis/webinator/search/main.xml?
pr=profile&query=query
Where HOSTNAME is the IP/hostname of your Webinator,
profile is the profile to search, and query is the user's query.
The URL path for your installation may be different from
/texis/webinator/search, use whatever normally appears in your
search URLs.