Here come the pictures of Dimmer switch " 6Q0 941 333 C" installation as I promised.
Full credits to Master Ciclo for guiding me in a proper way to finish the installation
Before attempting to remove the fuse box, footwell AC vent removal is must, otherwise fusebox cannot be freed.
Footwell AC vent removed.
After removing the 2 screws holding the fuse box, fusebox need to be pushed back slowly and slide it down.
Have to remove these 2 locking clips
Dome plastic cover, covering the bunch of wires need to be slided out
Wires concerned to us.. SB7a(light blue) and SB7b(dark blue)
Making the harness(self explanatory) before proceeding further. Taped it to prevent any kind of noise
SB7b isolated and taped
Dimmer switch connector(T6)
Connecting wire to slot3
Dimmer switch now connected
DONE!!!... Put back everything in reverse order and connect the battery.
Dimmer switch should start working now

Head light beam height control switch also works along perfectly.
The second part of installation, Isolating plate lights from Dimmer switch control, I have kept it pending. Will take it up later.
As of now, Plate lights brightness is Under control of Dimmer switch.