Remote central locking retrofit

[Zen535i]

Hi,
I am attempting to retrofit my late '88 535iSE with remote control of its central locking. I bought a BMW remote kit off e-bay, the receiver box is part no. 82 11 9 401 487, but am having difficulty interfacing it with my car! It has 2 sockets, one 8-pin, the other 24-pin.

Does anyone know where I might find the wiring diagram for this unit? I tried my local BMW dealer but they're policy is not to supply such details (I don't think they had them in any case.)

I tried hooking it up to the old Cobra 3190 alarm wiring behind the glovebox but it was only a single 20-pin plug, and fitting the receiver would self-close all the doors and windows but not operate with the remote. (The remote for the Cobra alarm was mislaid by the previous owner, hence the need to replace it.)

Thanks for any pointers!
Maurice.