Eventually solved the problem of transferring my address book to the 2006 SC 430 with the Mark Levinson navigation eventually, about a month ago. Used the compatibility tool at
https://secure.drivers.lexus.com/lexusdrivers/info/my-lexus/resources/bluetooth.do
and looked for a number of carrier-phone models until I found that the old AT&T Sony-Ericsson Z310a looked to be the best. Found the phone (obviously, used) for a few bucks on e-Bay and spent $10 on an AT&T Simcard. Downloaded my contact list (synchronized on my laptop from my iPhone) to the Z310a and then transferred it to the car - the last part was not simple - the sequence of phone actions and car actions did not always work and I just kept trying till it transferred.
Sorry kayjack that this may not be of help for you.