A 556 chip contains two timers, could do the job with the aid of a couple of relays and probably one inverter transistor.
When the courtesy dome light comes on (or the door lock plungers if you prefer), (a 12V rising? pulse), one timer activates a relay in parallel to the existing manual 'down' switch for half a second.
When the courtesy light shuts off (a going low? pulse) the other timer activates a relay in parallel to the upward manual switch for half a second.
Industrial time delay relays are more expensive, but can be implemented too, have the adjustable timing, contact and selection of pulse polarity all in one.