Nah, I wrote a completely custom command for the callasm command. It's fairly simple to do, all things considered. Also, my script is somewhat more simplistic, since mines just has the callasm, and then I just branch to the Milk Drink script to take care of the rest.
I've now written 5 custom commands for the game:
F9 (Store Half-Word)
FA (Store Word)
FB (Check Used Attack)
FC (Set Pledge Effect)
These sit on top of the existing commands, and the 1 index for all hack I applied to command 0x10. All in all, it works rather well.