Yes, it can be done. You just need to repoint the routine of 11,13,18,19,46 that is only:
jr r31
nop
to some free space and write your formula. Glain made an ASM that makes Formula 11: Damage = MA * (WP+Y). You can check it here: http://ffhacktics.com/smf/index.php?topic=7864.0
IIRC there is no allocated space for formulas >= 65, so it should involve some tricky ASM with formula call routine.
jr r31
nop
to some free space and write your formula. Glain made an ASM that makes Formula 11: Damage = MA * (WP+Y). You can check it here: http://ffhacktics.com/smf/index.php?topic=7864.0
IIRC there is no allocated space for formulas >= 65, so it should involve some tricky ASM with formula call routine.