100% correct, you need to use the 20v TPS - just wire it backwards to the 16v
i had to do this to my 16v, running 20v quads and 20v TPS, and stock 16v ecu/wiring..
20v tps side > 16v loom side
brown > yellow
Blue > red
Red > Blue
Yellow > brown
my write up i did a few years ago can be seen here... although the pics don't work anymore, and i probly would have run vac lines differently with the stock map sensor, and made a proper idle control... but when i did this... nobody else seemed to get one to run with the stock 16v ecu, and told me aftermarket was manditory... i was driving it daily for 6 months before going to adaptronic, ditching the map sensor, and using an RPM vs TPS tune..