Besides the in-game editor you can use Hobbits waypoint editor. The topic on it with download links is
here. The interface is a table editor showing all the properties (except co-ordinates). There is a
tutorial. You will need .Net 2.0 for the latest fixed version or .Net 1.1 for the older mildly buggy version from last June.
NOTE: Hobbits waypoint editor can only access un-packed .nav, .aiscript and .bsp files so use winzip/winrar to extract the .nav files to the normal directories and edit from there. (Also be advised that fritzbot may still select to run the pk3 packed versions, so you may have to move/delete the old file versions for your testing).
(and welcome to the world of waypointing)