Pre Populate webpage field via URL

I'm trying to pre-populate an input field on a webpage using just an URL. I would like to have users automatically have their connote number entered into the following webpage;

http://ift.tt/1PAqzUr

Something along the lines of;

http://ift.tt/1WUsfh2

I think it has something to do with the following hidden fields;

__EVENTTARGET

__EVENTARGUMENT

__EVENTVALIDATION

I've tried different combinations and have gotten the page to spit back some errors, but i'm not sure this can even be done?

Any help would be greatly appreciated. Cheers.