run 2 copies of bgb. load 1 pokemon rom in the 1st and the other pokemon rom in the 2nd. set 1st to link->listen and click OK. set the 2nd to link->connect. if you use the defaults (8765 for listening port and 127.0.0.1 for ip to connect to) it should then say (linked) in the title bar. presto? for more information open the "bgb.html" file and search for the heading "game link:"
EDIT: I'm making a quick video using red/yellow as a demonstration. it will not involve actually trading pokemon but only linking up 2 bgb instances.
You might have to reset the gameboys after loading the game i am not sure...if that doesn't work maybe loading the game first then running link. try out a few ways and see what happens
