Allright only bone, i'll tell u what i know.
Most buy the autoleads fascia, which gives you the option of single / double din, which fits perfectly, but colour & finish does not match the dash, so i went down DJ wozzas route of filling / sanding & painting to match,CLICK with drying times all in you could do this in a day but it will have to be fitted once totally dry, in total this would take all weekend, there is a original lexus replacement, unsure of part numbers but is more expensive and doesn't look so good, so your first decision there.
If you go down the auto leads fascia route you will require slightly longer bolts to fit the stereo to the fascia as the lex ones are very short.
If you have a sport or se 200, then you will need the autoleads amp bypass cable, disconnect the amp located under glovebox, and reout the cable to head unit, if you have nav, then another box of tricks is required.CLICKY
Taking the dash apart and fitting the unit is the easy bit, there is a picture walkthru from another site.LINK
This is how mine turned out.PIC
Best of luck.
Deckie.