As far as I know, it can not be done. However, I recently came across an article. If you download certain toolbars that reside on the prospects computer, it panda has a toolbar app. Well, when say I go to make a purchase, guess who gets the credit for it. "panda". So, the tool bar has to be high in existence, PLUS the person can get pushed "ADS" from it. See what I mean?
However, if say I had a website where I could rewrite the cookies on my web visitor machine, guess who get the credit "George knocks".- angle in the outfield?