Since nobody has bothered to answer, I'll try to add some useful information myself for those with pre-MY 2007 Mk5-s.
I bought the aforementioned rear door modules off of a 2005 Golf Plus and while their VCDS measuring blocks show no sign of exit warning lights, there is a measuring block for door handle illumination. When the module is coded for handle illumination, the block's value changes to 100% when the handle illumination is called for.
I have opened up one of the modules and observed the module's printed circuit board against a light and after a process of elimination, I've come to the conclusion of either pins 5 or 8 of the 18pin connector are the +12v for door handle illumination.
Who is willing to give it a shot?