There are several steps:
1. Take out the center cup-holder (it pops out with a little tug upward). unscrew the 2 screws.
2. On the shifter (lower part) there is a cover that covers 2 screws, unscrew and remove the shifter knob.
3.Take a pick tool and lift the shifter bezel console (black) it also pops up.. there are 3 or 4 connecters (disconnect with a small flat head screwdriver)
4. Once the shift cover is removed, there are several screws and tabs holding the bezel trim down unscrew the screws and lift bezel trim up,
5. Disconnect the ash-tray (blue connector)
6. Disconnect the hazard signal control , volume control connector and the climate control connector.( On the left side)
7. There are 4 screws holding the the radio and climate unit cage to the dash frame. (unscrew)
8. Now it gets a little tight, pull the unit towards you slightly and disconnect to connectors for the climate control unit (on top) and the factroy radio (on the bottom).
9. Next remove the radio and climate control unit from the cage(screws on the sides).
10. Next you will need a new cage: Metra 95-8157B Double DIN Installation Kit for 1992-2000 Lexus SC300 and SC400 (Black)
by Metra Link: http://amzn.com/B001TJG7SA
11. You will need the following harness: Metra 70-8112 Radio Wiring Harness for Toyota Amp Integration 15 Pin
and/or Metra 70-1761 Radio Wiring Harness For Toyota 87-Up Power 4 Speaker
by Metra Link: http://amzn.com/B0002BEQJ8
12. Match the wires according to the metra kit and new radio instructions.
13. Next follow instructions in reverse for re-stall