I have modified ours
I have modified the front interior light on our 300TE so that at the end of the time delay it fades out over a period of a few seconds rather than turning off. It involved additional circuitry. I also modified the rear interior lights on the C-pillar in our wagon. I added a circuit to allow them to fade to off (over about 10 sec) and also added a small rocker switch to each so that rear passengers can operate them individually from the rear seat without the need for the driver or front passenger to activate both from the dashboard. For the circuit to achieve the fade to off, I would have to look for that. As to how I integrated the extra circuits and the switches, I notice you are in Sydney, why not come along and join the MB Club here and I will show you it all in real life!
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.