Ontraport Pages: URL parameters and merge fields.

It would be great if we could pass a Contact ID or other unique field to ontraport pages via a URL parameter so that we can retrieve additional data about the contact using merge fields on the OP Page.  I created a WP plugin utilizing OP's API that achieves this on our Wordpress site, but utilizing the API is a little... slow.  Would be nice if we could achieve this from within an Ontraport Page.