I am in the same boat as you. I have 2009 ES 350 Premium used to have a 2007 Nissan Altima with Navi. There mod was super easy installed Single pull single throw switch after cutting one wire. It then allowed you to play DvDs, enter address, etc (access any function in the nav system you wanted to) I would assume the lexus should not be any different. On the back of the navigation there are two wire harnesses. What I would do is drive with someone once you pull the navigation off get on the highway set the car at 60mph in the right lane and use a wire tester find out which wire on the lexus is the speed wire. Go to radio shack pick up the wire kit its about 10-20 bucks use the Green one that is about 20 ft long in the kit but the 3-7 dollar SPST switch from radio shack or home depot or menards. Cut the wire attached to the harness somewhere in the middle of the length then cut the green radio shack wire in half install half from the nav and the other half on the wire side attached to the MPH gauge put the switch in the middle and PRESTO! Switch off = car thinks going 0 MPH and you can enter whatever you want. (notice the triangle on the GPS will stop moving when switch is off
*****IMPORTANT*****
Leave the switch off for long period of time will take a while to recalibrate your location so if you have it off drive twenty miles then switch it back on the GPS may say you are not on a road or show you in a lake or something until it re-calibrates your correct location.
COST= $20-50 dollars
