Unzip to your jEdit settings directory (e.g. c:\documents and settings\YOU\.jedit)
The most important new features are:
- completely rewritten parser (best used with "Parse on keystroke" - See
Plugins > Plugin Options > SideKick) (the new parser is created
using flex and bison so very closely mirrors the actual lilypond parser)
- instant compile - LilyPond will be called to compile your file in the
background while you are working, and the PDF preview is updated
automatically
- compile on save
- a lot of bugfixes
This release should be available from jEdit plugin repository in 1-2 weeks - I'm waiting for bugreports until that :) Send them to the bug tracker at http://sf.net/projects/lily4jedit