Simple? Yes. But it's an awful amount of boring work.
You create or change hotkeys by editing a file called lotr.str. In that file, you will find every single piece of text in the mod, including abilities or recruitment texts for your units. As an example, let's look at the code for the Wizard Blast:
CONTROLBAR:WizardBlast
"Wizard Blast (&Y)"
END
The letter behind the "&" symbol determines the hotkey. If you don't have that symbol in the description, no hotkey is assigned at all. So if you wanted to change that hotkey, you would just put something else there that isn't already taken (like D/F/G for stances, Q, E, A,...).
But that only changes the hotkey for one ability. If you want to change hotkeys for everything, you'd have to look up every single string to make sure you edit the right one, and then edit that hotkey. And Edain has hundreds, if not thousands of strings that you would have to edit.