you can make an shtml file, make the like to the gallery like:
http://www.yourgallery.com/filename.shtml?AFF_ID_HERE
Then in your links to the website, where you need the AFF ID to be in the link you put <!--#echo var="QUERY_STRING"-->
ie. http://www.ccbill_long_ass_code?ID=<!--#echo var="QUERY_STRING"-->?html=tour.com
but make sure your server is set up to work correctly with the shtml files.