GrubEd is a graphical GRUB menu editor that supports MD5 password generation.
GrubEd should be run as root either su, gksu or pfexec. Note config file is backed up if run as root.
The backup file will be named with a '.grubed' extension. You might wish to look at BigPond.net.au Grub page GrubEd was built on OpenSolaris but should work with any modern Unix type system that supports Gtk and pyGtk.