Scirocco Register

Been getting ready to fit the smoked indicators I got from Eurowagens, noticed on the back that there appears to be wiring to a holder inside the lens connected to a holder with a W5W bulb

Question is, how hard is it to wire in? Or is it worth doing more rather?

Probably get a US-market wiring diagram (or ask on Vortex). That's how they were originally over there.

Just connect on parallel with the "normal" front sidelight.

Obviously only do this if it's going to show white light to the front, or if you don't mind occasional hassle from arsey dibble, and know a bent mot tester

Couldn't you connect a normally closed relay in parallel with the indicator.
This way every time the indicator flashes the sidelight in the indicator will go out.

Done the same on mine with a set of clears, just wired the small extra bulb up to the standard side lights then an amber bulb for indicators (or chromed bulb for added coolness!)

US regulations require side marker lights - amber in the front, red in the rear, to be on when the vehicle lights are on, including just the parking lights (first position of the headlight switch).

The US cars do not have the small city lights inside the headlights, however. I would say the easiest way to wire these lights would be to connect them to the city lights. I am almost positive these front side lights do not flash with the indicators, but rather are always on when the lights are on.

Mk2 Scirocco taillights for US cars have a similar provision - an extra spot for the small rear marker light on the very side of the taillight.

Tbf they just popped out so popped them out and covered up the hole, easiest option!