how to make a spell differ when cast by Charname vs. others

[subtledoctor]

At the simplest level, for reasons of inter-mod compatibility, I'm wondering if a spell could be coded to cast two subspells: SubspellA would be invoked when the main spell is cast by the protagonist, while SubspellB would be invoked when the main spell is cast by anyone else.

Possible?  Would it need (cold shiver) scripting?  Would much prefer if there was a way to distinguish via opcode 318 or 326...