this hack uses the 'sponsorimg' field in order to display the rest of the fields. I do not use the sponsorimg field (don't like to display sponsors logos). If you install it and don't include an image for the sponsor, don't expect it to work, but the hack of the hack is easy...just a heads up...
just change this line:
if ($forum['sponsorimg'] && $forum['cancontainthreads']==0 && $depth==1) {
to
if ($forum['sponsorurl'] && $forum['cancontainthreads']==0 && $depth==1) {
(assuming you included a link to the sponsor's site)