Does anybody know how to get an external output from a clifford concept 600 alarm when the extended proximity sensor is activated?
I want to use it to remotely turn on security lights.

Unfortunately the 600's dual zone proximity sensor output is multiplexed and only decipherable by the alarm, and there is no trigger ouput from the alarm for when the external zone is triggered other than data to the siren for making the appropriate warn-away noise.

Or do you mean can you use another extended range receiver compatible with spare channels of your Clifford remote so you can turn on your security lights? If so, speak to your local Clifford dealer about the DEI 3-Channel Garage Door Receiver which is an easy DIY system.

Thanks for the answer max, your first interpretation of my question was right. At least i now i cannot do this, saves me from trying anymore.

But could you not simply mount the PIR that controls your security lights in a position that 'looks over' your car? Or just get one of those cheap all in one 500w halogen floodlights with built-in PIR mounted overlooking your car? I hate those things, but I guess the villains do too as it lights them up clear as day (-:

The problem then is that everything will turn the light on (people walking along the road etc..) , rather than just movement on my drive.

I'd pop into your local electrical wholesalers and get a decent PIR detector for switching lights with that is fully adjustable so it will only cover the area you want. Should be no more than £15-20 I reckon. Positioned correctly I'm sure it will give the desired effect