There are a lot of resources available from the above links you have provided.
I think the following link from [url=http://jmusic.ci.qut.edu.au/jmtutorial/t1.html]jMusic tutorial page[/url] might be useful to your project:
  [url=http://jmusic.ci.qut.edu.au/jmtutorial/BasicGameTour/BasicGameFrameset1.html]Introduction to music for Java computer games[/url]

According to the document: You should be able to create different notes(frequency)  at run time.