I have a LHD 2.5 over here.
Took the ECU out plenty of times.
Take the glove box grab handle part out. There is a screw on the front of the ECU which snugs it to its fram. There are two big bolts in the engine back right behind the ecu that need to be undone. This allows the ecu in its fanto be yanked from the firewall. Then there is a screw holding the harness connector to the ecu. Undo that screw and gently lever the connector off the ecu. Of you need them I'll post pics.