Is there any way I could auto-fill the fields on this registration page?

I have a link to a registration page: Registration Page

When I take users to the page, I'd like to save them a load of time, frustration and calories to burn, by filling in the fields automatically.

The whole form is ran in JavaScript and JQuery by the looks of things, but I have no idea where I would start to actually do something like this. I have the users details (to input into the fields) in a SQL db, so some PHP parsing to start off with.

Any ideas where I'd go from there?

SORRY,forgot to mention: I don't have any moderation access to the Reg page.