There are programs out that try to do exactly what you are talking about. The app I recently bought is called Songbook. It's a fairly poor attempt as far as a GUI and input method but the underlying format is a small set of HTML command structures that put chords above lyrics in "chord pro" file format and I think there is a way to define your own chord shapes. Here's a link http://webchord.sourceforge.net/ If you know of a basic ASCII text editor for android that will let me assign macros to virtual keys and view XML files, let me know.