I'm working in the jobs of my game, and had thought about doing a necromancer job. I don't know much about ASM hacking, but this is not difficult, so:
<Patch name="Formulas 5A,5B,5C and 5D used Undead instead of Dragon">
<Description>Formulas 5A,5B,5C and 5D used Undead instead of Dragon</Description>
<Location file="BATTLE_BIN" offset="1205BC">
Indeed, that sprite you plan to use?
I find this (By Jon) but is incomplete...
So far I think the best is the custom sprite ''Enchanter Male''