Lots of work I am afraid. Very much work.
What compiler do you use?
If you write with a classic interface, I have a generator which creates a source based on a screen layout. You get a kind of database-program in which you can scroll up and down, one-to-one with the screen. You can modify the source after that.
My compiler is CA-REALIA. If you create a layout 80 characters width, 25 lines long (the pc format, not the mainframe format), and you place it here, I'll generate a sample program, only, the source uses some screen handling routines in my environment and that means that there will be a part you have to write yourself, probably using a screen section or so.
In the layout you use the # symbol to create a numeric field and a @ to create a alphanumeric field. The amount of #####... 's will also be the length of the field.
I'll put the generated source here on the board.
I'll hear from you I guess?