Sorry I haven't got back here in awhile - been busy helping other owners replace heater boxes/cores/hoses etc and also starting to build a new engine for my own P38 - so haven't been online as much as usual.
I'll try and help clear up a bit of confusion around the locking switches etc..
The tailgate locking/unlocking is done through the Right Hand Front door, on both RHD and LHD vehicles. The only difference between RHD/LHD vehicles in regards to the latch is that the key switch changes side to match which door you put the key in. BOTH front doors have a CDL (central door locking) switch in it, which will tell the BECM the lock/unlock state of that door - and also control the central locking of other doors when the sill button is pressed down. The tailgate unlock motor is supplied power from the BECM, and the ground to the other side of the motor is controlled by the CDL switch in the RH door (it's not an additional switch in the latch, but rather just a splice in the loom) - which then either enables/disables the grounding of the tailgate motor (via the push button on the tailgate).
Being a '96 the method for entering the EKA will be one of 2 ways - both of which have been described already so I won't repeat it... If it's the earlier type, then you don't need the 4x turns to LOCK to begin the EKA sequence, you just start with the first digit of the EKA to lock. Unfortunately there is no documentation to actually say where the change in sequence happened, or what software version of the BECM has the additional 4x turns to lock to begin the sequence. My suggestion would the to try both ways, but if it isn't entering or being recognised, then make sure you open/close the drivers door after 2 attempts, and this will reset the counter... 3 unsuccessful attempts will give you KEYCODE LOCKOUT again, and you then begin the waiting game again for that to clear.
I would definitely be checking the door latch microswitches in the drivers door, to make sure that they are all working properly and that entering the EKA is actually possible. There is no point continuing to try and enter the EKA if there's a problem with the latch.
If the latch checks out, and the same with the RHF door, and the EKA STILL won't be accepted, then it's probably time to pull the BECM out and send it to someone like Myself, Callrova, All Car Electrics, or any of the other places that do BECM unlocking, as if nothing lets the EKA be entered, then it is entirely possible that the BECM has gone into an alarm lockout, and in addition to it not accepting the EKA at all - it can sometimes corrupt one of the digits of the EKA code that's programmed (I don't know if this is a fault, or a 'protective measure') which means that even if you have the correct code, and are entering it properly, it won't actually match either.
Check the door latch switches before anything else. Then at least we know if it is even possible for the EKA to be entered/sent to the BECM correctly.
Regards,
Marty