you need to put it somewhere into Emacs' load path and add the symbol
`SYS' to the list `vc-handled-backends'.
-*** The customizable EDT emulation package now supports the EDT
+** The customizable EDT emulation package now supports the EDT
SUBS command and EDT scroll margins. It also works with more
terminal/keyboard configurations and it now works under XEmacs.
See etc/edt-user.doc for more information.