editing banks_default.txt

I want to expand my midi instruments beyond 127. It seems possible to edit/create a new bank file. Has anyone done this. I’ve tried adding new lines, changing instrument numbers etc, but I’ve got wrong format errors (or something like that) does someone have an example of a modified bank file that works?? or steps to create one?? Still using Version 3.3

I’ve got some down on http://downloads.phootoons.com/