That diagram is for a Subaru is it not?
I'd advise being cautious with any Unichip wiring diagrams you come across. From what I'm led to believe, there are several variations of Unichips and they don't all share the same pin configuration and wire colours.
There's also this diagram which is supposedly for an ST205 Celica:
But again I wouldn't take it as gospel and risk using it to wire in a unknown second hand Unichip. Second hand Unichips seem to be more trouble than they are worth. Taking everything you have with your car to a Dastek dealer is probably the only sure way of getting it working correctly.