I developed a simple way to pass parameters to Webdirect for low volume applications. This solution will fail if two people in the same office access webdirect at the same second, so it is best for remote worker or client access.
1) pass a parameter to a URL
2) The URL is a PHP site that places the parameters and the IP address into a table in a Filemaker database. The PHP site redirects to the webdirect page server side so that there is no delay in redirection. This page can be hosted anywhere.
3) Your "On Open" script in webdirect will do a find on that table for your own IP address get(systemipaddress) and will use the parameters and will delete the IP address from that table. I have found the total transaction time between PHP and Webdirect is under 1 second, and under 3 seconds for the webdirect page to open which is more than acceptable for the web.
If this is still a hot topic for anyone and anyone wants an example then I'll post one here. I'm thinking of adding a simple demo that you can hit on my webpage.