What I had was a 2001 Jetta with the Monsoon system, but when I bought the vehicle the previous owner took the radio out. All I had was the OEM connector sitting there. I then obtained and installed a radio that claims to produce 50W for the speaker outputs. At this point my wiring harness was the typical purple wire connects to the other purple wire ect. I then ran into the problem where the amp wouldn't turn off.
When I make my harnesses I typically use flat spade connectors to connect the radio harness with the harness that connects to the OEM connector. Because I did this, I was able to change my connections fairly easily. I ended up making a separate small harness with the resistor included in it, that I could connect and disconnect from my spade connections. But this extra harness was only because I was experimenting and thought I may need to take the harness apart.
If I were to do it again, knowing what I know now, before I put the spades on the OEM connector, I would twist the resistor leads with the wires from the car side of the harness with LF- then crimp on the spade, I would take the other resistor lead and twist it with the gnd wire, then crimp on my spade. Then I'd heat shrink, electric tape or what ever, such that this resistor doesn't short with anything else like dash components. Once the spades were done, I would then connect it to the radio harness by pushing the spades together.