I am 'in the same boat', yet because the other parts of the loom are there, the green block must be there somewhere.
I have had a good look at the manual, and the connector block is on the end of a long length of loom, all on it's own, so it will be tied back and taped into the loom somewhere, but could be up to a metre away from the ECU mounting point.
If someone is breaking a Supra with loom, without cruise, it will be a lot easier to find.
A few months ago, whilst standing on my head under the dash removing the dreaded ding dong, I seem to vaguely remember there being a spare green block behind the kick panel fuse box, if no-one has the answer, I will have that out at the weekend and take a look.