Lol. It was dead easy but it doesn't run. HAHAHAHAAH
The astra GTE ECU loom has a square connector above the glovebox.
Connector the following wires to this.
Pin G Thick red to battery +
Pin F black (ignition) to the cavalier's single connector with black wire by the dissy.
Pin E red/blue (fuel pump) run to the drivers footwell and connect to the same colour wire with single connector.
This is all you should need to get the engine running.
Right the rest of the wires can be done in different ways.
On some cavaliers, some of the wires are available at the round plug for the engine loom by the battery so you can connect to these. If they aren't then you can run them into the car to the drivers footwell.
Pin A brown/blue (engine light) - by battery pin 11
Pin B brown/yellow (fuel computer where fitted) - dr footwell black/brown.
Pin C green (revcounter) green wire under dizzy with single connector or by battery pin 9
Pin D blue/red (MPH - probably not required) - drivers footwell.
Another problem is the dash engine temp gauge. Not to sure how this works on GTE. But if you find a blue wire connect it to the round connector by the battery pin 10 or dr footwell.