Question: Changing a Battle Command to a single spell

Hello everyone! 

   I'm still new to FF3 (SNES) romhacking, so I'm not sure if this is incredibly simple or incredibly complex. Really, I'm mostly trying to understand basic concepts. In an attempt to learn small bits of hacking, I've been diving into the Hex Code as much as I can. I've done some event hacking, and now I'm moving on to actual data. I'm trying to set small goals for myself for the time being so here is my current goal:

I'd like to change Sabin's Battle command list from Fight, Blitz, Magic, Item; to Fight, Blitz, Charm, Item.

My original idea was to set Sabin's third ability from Magic to Mimic (a command I don't intend to use) and change where the Mimic data points to result in a different effect. I figure I can do this by either pointing at the "Muddle" spell, or the enemy spell "Charm" (Entice) which is used by Chadarnook. Logically, if that's how pointers work in this instance, this would give me the option to use any spell there: Fight, Blitz, Fire2, Item. Etc. 

Is this how pointers work? Am I completely off-base? Is there a simpler way to do this? My thanks in advance for helping me understand this simple concept.