First thing o do is get hold of some small lights, i used some bootlamps out of a scrapped fiesta ghia. Anything will do as long as it is small enough.
To make the gaps in the trim for the lights to clip into i used a drill and a knife. I first Marked out the size of the required hole and used the drill to drill along each line, do this carfully as you do not want to damage the body shell which is just behind the trim. I then used the knifew to make the cut out the perfect size and to give it a clean cut.

The next step is to wire in the lights, to do this you must connect to wire to the drivers side courtasy lamp and feed that through the gap you have just made (You will have to pull the trim away to feed the wires through. A good place to hide the wiring is under the door sill trim, just unscrew this and run the leads along this. Connect the live to a permenant live at the fuse box using a scotch lock connecter, best is to use the live used for the current courrtasy lights (Fuse 2). Then connect the earth to the plunger switch on the door, again a scotch lock connector is to be used. this will now make the light work when the door opens.

Now we have to connect the passenger side light to the drivers side. This is simple enough an the wiring can be hidden underneath the seat and carpet.
Now you can push the lights into their respective gaps you cut out and tidy up any loose wiring. This results in some very useful lights for entry to the back seat sin the dark.

Finaly, if you wish to put a switch into the circuit so you can switch the light son when the doors are closed, say to light up the ash trays, then read on.

Locate a sutible place to put the switch and drill any holes needed, i placed my switch just forward of the fuse box in the small rescess.