With a quick googling...: http://download.oracle.com/javase/tutorial/deployment/applet/param.html

I'm embarrassed 
I did search around, but I guess I didn't quite have the search terms.    Thanks for the find - I'll look it over.

I can't get that to work.. JNLP is not a applet, so I'm not sure.  I tried the

1. <param name="paramStr" value="someString"/>

and then calling 

1. String inputStr = getParameter("paramStr");

returns null.

This seems to work.. need to determine the offline effect as I don't want it included if launched offline.

JNLP FILE

1. <resources>
2. <property name="key" value="something"/>
3. </resources>

Processing

1. String prop = System.getProperty("key");
2. println(prop);

String trying to figure this out... <property> works, but it requires that the jnlp be signed (generating it dynamically). 
So I'm still trying to get <argument> to work.

The simple answer to some degree is that Processing stores the arguments sent to main in the String[] args.

So this should display it..., but it doesn't

1. for (int i=0;i<args.length;i++) {
2.          println((String)args[i]);
3. }