HTTP API facebook parameters

I want to be able to track when one of my users see my facebook page, so am using the same approach as: Non JS Tracker on Facebook fan page.

My tracking works, and I can see the visit in the database, and can pass set parameters across i.e. action_name=asdf, will put asdf in the action column.

What I want to understand is how to create the parameter values dynamically. Specifically I would like to set the same visitor id as the normal tags on my site - at the moment they are different.

Is there anyway to do this using this method?