When I did this some years ago on the 97 JE I had then, I took the signals from one of the rear lamps. I didn't have a diagram then. I have now, though, so if you write me an e-mail, I can scan the necessary pages for you.
I have been a lazy b...... but here they are at last, the scans - R276 is the connector in the fuse box where the official kit takes the signals:
And this shows the relays in the fuse box: