Hi,
I can't answer your question directly, but I maybe I can help you with a hint.
Michael Schilli (Author of
PerlPower (Goto Perl in german) and one of our favorite Perl-authors in Germany) has
actually written such a tracking system (using cookies and outputting graphics) already.
It was described in two articles of ther (german) linux-magazin. I don't know whether you are capable
of speaking german, or whether the babelfish can help you out, or if the
sourcecode is just enough, but here are the links.
Again: it's all in german.
Regards
Stefan K
$dom = "skamphausen.de"; ## May The Open Source Be With You!
$Mail = "mail@$dom; $Url = "http://www.$dom";