After MANY attempts at getting this to work I finally did it.

The trick is this: the directions say there is a click when you first press & hold the unlock button, then a click five seconds later, then, to get all doors to unlock, there is another click, 10 seconds later.

This is not quite right - when I first press the unlock button, there is a loud click & a soft click - neither of these clicks "count" when counting the clicks! (This was my mistake). About five seconds later there is another click & about five seconds after that, yet another. THAT is the point at which to turn the key back to the I position (it is in the II position for the duration of the programming; note that the II position is not the position with the car running, it is the position just before that - I, II, and III are marked on the ignition itself - that was another of my problems....).

Therefore, there are technically FOUR clicks in total - I was turning it back to I after the third click and nothing was changing (because that was how the car already was programmed). I now have all four doors unlocking when I put the car in P.

Hope that makes sense & helps!