Julia,
No, unfortunately we didn't in the timeline we were working in, so we eliminated the process and implemented java script in the form that did it for us instead. We took it from a post on the Artisan blog, I believe this was it - http://eloqua.blogspot.com/2009/04/lead-source-codes-capturing-with.html - and it works very well. You just have to know how to work with java script (which I do not, but thankfully, I know someone who does). I'm sorry I can't be more helpful as I realize how frustrating this issue is first-hand.
I hope it all works out for you!
Kristin