What year are you putting it in? You should put some info in a signature that'll show your year for all your posts.
Anyway, the ****** cooler in the rad is a closed system so just plug the holes (it'll probably have plugs from the factory) so you don't get crap in there if you already have the external cooler plumbed. Sorry no part numbers for the fittings to connect to the in rad cooler but if you find them you can just get some ****** line hose and some clamps and run it. I don't think it matters whether it goes external cooler then internal or opposite. TwoBobsKJ had some pics but the internet demons have deleted them. Sounds like the consensus is that the in-rad is better and both are good but if you are in a cold climate both could actually keep the trans from getting to the right temp.