I agree that mod_usertrack is the Right Way™ to do it; it's too bad you don't have that luxury.

Are you sure you need that sort of granularity though?

If the site gets a reasonable amount of traffic and you log referrers you might consider just analyzing the aggregated data. Unless you are looking for something very specific or need it for debugging, it's likely that you'll find yourself munging your click trail data down to something that looks like referrer logs in order to gather statistics on it anyway.

-sauoq
"My two cents aren't worth a dime.";