I have done some JavaScript but not with XML/XSL. Are there some good
tutorials on this subject somewhere?

Tutorials? Hm. Check
 http://msdn.microsoft.com/library/default.asp?
  url=/library/en-us/xmlsdk30/htm/xmconxsldevelopersguide.asp
(undo linebreak)
for some stuff for MSXML (IEx 5.5 and later)

For Mozilla, there is some material on
 http://www.mozilla.org/projects/xslt/js-interface.html