I'm still trying to figure this out. I;m sur this is a simple question that "someone" out there can answer...
as a wild newbie guess I'd say try putting the jar file in the lib directory of the war file... If that doesn't work there's a way by packaging the application in an ear file and having the manifest.mf of the war file have a Class-Path: myjarfile.jar line (with a return after the line). Then place myjarfile.jar in the root directory of the ear file with the war file, so that the contents of the jar become a "downloadable" extension of the war file. I may be way off but as noone responded I thought a guess would be better than nothing.