Hello Captain Frank. Maybe the 19 readers wanted to read your whole thread but do not have a sensible answer to your question. After many years of being here I believe that this is the first time someone wanted to add aftermarket seat heaters with using the factory butttons. You are correct in getting the JTIS disk.
Please post back once you get the heaters working as maybe it will help a member down the road.
Also please stop by the "New Member" area and introduce yourself per forum requirements. It will aid you in becoming a full member with access to more information on this site.
Good luck with your project.
2005, S Type 3.0