Please excuse the thread drift. DMed EOD guy but thought in the balance, this would twig others also into adding AUX switches in an OEM looking fashion.
@EOD Guy. Are you taking about the switch panel from 300mods in Australia? If so, I got the same, and unexpectedly found it does not work... Unfortunately because the side supports of the panel are not centered vertically, it seems the design will need to be mirrored left to right to work on left hand drive cars. Unnecessary difference in my opinion, makes me think less of the Toyota engineer in charge of this. Thought they were all about minimizing unnecessary differences and parts... Anyway, I asked Bob nicely, which seems like a really nice chap if he'd be willing to do this extra bit of design work so his product would work in NA. Lets see what he says.
On the cutting of the plastic of the panel in the middle to make room for the extra switch, I found that if done carefully and judiciously, you lose very little as the middle leftover tab will still provide some friction in the middle to prevent the panel from bowing out from the "unsupported" middle while still providing enough room for the extra switch.