Sorry, it's not that simple (or possible). SimpleViewer actually requires Java 6.
There were several methods and classes that were introduced in Java 6 which made life much easier when coding the skin. If I remember correctly, there were at least thee or four separate areas where the code could be greatly simplified by using Java 6 so I took the decision to use the new methods and classes available and for the skin to require Java 6 back in November 2011.
The last version of the skin which will work under Java 5 is v5.12.1 (15 releases ago) and it can be downloaded from the skin's download page here. (Click the 'Show all' button and scroll down.)