automatic locks with RKE?

My (power lock equipped) 98SL2's owner's manual has a bit about changing
the state of the remote keyless entry system so that it can arm itself
when you exit the vehicle. The dealership says this isn't possible.
The manual also specifically says that the system will not lock the
doors in this 'auto-arm' mode. (You can still lock the doors with the
key fob.)

Has anyone experimented with wiring or reprogramming the RKE system so
that it will auto-arm *and* automatically lock the doors? I really
don't want to install a third party keyless entry system, since I
already have one.


-rj
98SL2