It is theoretically possible, and has been done at least once. However it is not easy, and likely to be expensive.
Lexus won't do it, so you need to find the parts second hand, and then fit it yourself. You need the screen, CD unit and the complete wiring loom, including the stereo connections. They crop up on ebay every now and again and go for anything between 500 and 1000 quid. I think the whole interior needs to be removed to run the wiring through the car.
Ian