How can I make a follower use an unequiped spell when the player cast a spell?

[Sunspot2]

Well, the title says it all. I'm trying to make a follower to use a spell when the Player use a spell through a hotkey (I mean I the player uses a spell through a hotkey and want this to make the follower to do the same.

 

Maybe is possible to set the same hotkey to both spells? (The Player spell AND the follower spell?

 

Maybe is possible to addspell to the follower through a script in the player spell?

 

I really never modded a follower and have no idea how to do it.