Doesn't look anything specific to JBoss. Servlets forum perhaps is a better place, but i don't understand what you mean by "need to access". What kind of access? You have want to refer to the java classes packaged in a different war file? If yes, then why not package those classes in a jar and then include them in both WAR1 and WAR2?
I'll let this thread stay here for sometime, because i am not sure where this one fits best.