Not the easiest schematic to follow, but it's all there.
As the IS was rushed to market in '99, this cable setup was thrown together in a Rube Goldberg sort of way since the hinges on the Tourer caused the lids to hit the bottom of the trunk (whoops). Fortunately, I had one interstate fully set up to use as a guide for fixing the other IS bag cables.
Two cables per bag, fore and aft (#s 25 and 27 in the front, and 26 and 28 in the rear). They attach to the lids with a screw through a slotted clip tapping into plastic bosses (threaded holes) on the underside of the lids.
http://www.servicehondapsn.com/fiche_section_detail.asp?section=4224016&category=Motorcycles&make=Honda&year=1999&fveh=188145