Guys, the CEL is a misinfomation. Owners of the IS250/350 were unplugging this connector thinking it is a DRL resistor whereas it is the fuel pump resistor and this results in the engine shutting off. There are no CEL on IS300 with unplugging the resistor.
The IS250/350 DRL can be diabled by the dealer. They need to re-program your "CBEST" options.
As for the switch, there is a DRL relay (not resistor) under the Instrumental panel right next to the steering column. Tap into this wire instead since it is closer to the Instrument panel and you can run a very short wire to the blank covers next to the coin holders. Install a radio shack switch there and you are done
04 Manual: Borla, L-tuned sways, PLP Front Strut bar, TRD Rear Strut bar, CDD and TDD defeat, DRL switch, Headlight Aim control