I just installed lockpick 3 ultimate in my 2008 RX400H without ML audio and rear DVD. Yes, it does work with our cars, despite what the phone person may tell you.
In general you should follow the instructions for the RX350. I am adding a few poitners which may help someone in the future.
1) For the lockpick NAV unlock, all you need to do is to remove the rear right plastic compartment in the trunk. It's the compartment next to the middle compartment that holds the jack and various tools. The back of the NAV unit is right below the right compartment. You don't need to remove anything else.
2) When installing the ultimate in the front dash, you have to pull hard on the trim that holds the heated seat buttons. I was cautious at first and the thing wouldn't bulge at all. Use more force. It's going to be hard to damage it.
3) The lower audio unit (cassette deck and cd player) is held by four 10mm bolts. Two are easily accesible and two are hidden. It's going to be extremely hard to put back the two hidden bolts, so don't bother - it's not going anywhere after you put everything back together.
4) There is a very obivous route to get the video and audio inputs into the glove box, and it works really well.
5) Put a towel over the shifter and the surrounding leather in the shfiter area. The edges of the trim and audio units are quite sharp, and will leave marks on the leather. It doesn't help that the backing material beneath that leather is just styrofoam.
The rear took me 5 minutes. The front took about 45. If I do it again I can probably do everything in 15 minutes. It's definitely an easy DIY.
