I'd be glad to but as I can't run that gui I wouldn't be able to test it and going back and forth without myself being able to test it first would be a huge mess, especially when trying to get the positions correct.
But in a very general nutshell, here's what to do. Jump in, the waters fine.
1. Make a backup of your existing menu.ini file. Only work with that copy.
2. Copy the shells info. you're wanting from a menu.ini that has it in it. I.e., stock. An easy search of the file will find what you need.
3. Paste that info. at the end of the relevant section of the file. In this case from my earlier glance at the file, the G38 section may be where to look. But via your search of the file, double check this.
There is another way to add info. to the file but use this way for now.
4. Now renumber the entries you put into the file. I.e. if the last number of the last existing entry in G38 is G38 I10, the first entry you put in would be G38 I11. Each new entry you put in gets the next number in sequence.
Make sure this is right or the game won't load.
5. If not present in your install, add the relevant .tga files to it. Their name and location would be in the file entries you copied from the file you're using to work with.
6. Note the Position line in the entries. You will need to adjust these to fit where you want the icons to show in the gui.
7. When done, save the file and make a JSGME mod folder to install it with. Do not simply copy/paste any files over the existing ones unless you enjoy re-installing the game.
At one time there was a guide to working with the menu.ini file somewhere. Maybe try a google for it.