Open war3.mpq with the War3 Model Editor, and go to "Units"
Search for the files "CommandFunc.txt and CommandStrings.txt", first is to determine the location of the button(s) in the UI and second one is to set the strings of the command (tooltip).
You will need to export those two files, edit them and import them into your map using the same path (Units\Name.txt)
Thats the only thing you could do with them. Other than that, theres no alternative to replace them with an ability.