I've given some technical advice to others who have successfully installed an IHF1000 in other Lexus models but not in an RX330.
The IHF1000 installation manual includes the following text on page 11:
Note: The system's handsfree audio has been optimized for the external speaker. Routing the audio output through the vehicle's entertainment system may alter the handsfree audio performance.
But if you really want to use a door speaker, Google "Motorola IHF1000 adapter harness" and you will get a few hits.
Maybe a harness from http://www.quickconnectproducts.com/Find/find.php would work although it might take a bit of hardwiring too.
If your installer can't install your IHF1000 without a harness, he might not be all that competent. As long as you hook the phone kit's mute wire to the radio and/or amp so that it mutes the radio while a phone call is in progress, it is often/usually possible to splice into a wire leading to a door speaker. But if it was me, I'd use an external speaker per the IHF1000 install instruction instead.
IMO, the key to getting a phone kit to work properly is to make sure that it mutes your radio automagically when you make or receive a call.
I was thinking of Using the external speaker if there is no otherway of using the factory speakers instead. Surely there must be someone on this site who has successfully installed an IHF 1000 in there RX before dierctly into their speakers.
