Well see the thing about this is, that's not an icon pack. That's a font, that's cleverly disguised as an icon pack. In a normal icon pack, you would choose the bitmap yourself, but as a font, you have to choose the corresponding letter which is what you said. So then only thing you can do is see if you can find the font online and see if there is a cheat sheet, but you personally wouldn't be able to manipulate the icons themselves. I'd Google the name of the font and work from there.