You need a NULL MODEM ADAPTER and 2 serial PC cables to "clone" the handhelds.
The null modem adapter can be found on ebay for not much, and hopefully you have 2 cables from all your scanners.
Ensure the adapter has the correct gender changer on both sides (as both Uniden cables are female ends).
Just a note the 396T will not clone directly to the 396xt (you may know that but just pointing out for other members in case they try it)