SSL Detect Redirect

I would like to find a way to detect if our SSL certificate is
installed locally on the clients computer and redirect based on if
it's present or not. We self assign certificates and do not have the
need to buy one. Since the release of IE7, users are now getting the
"There is a problem with this website's security certificate" page
and are not continuing on. We have a way of installing the certificate
through a web page, so I would like a script that would check if the
certificate is installed and sent them to the secure page if not
redirect them to the certificate install page. Does anyone know if this
is possible?