First thing to do would be to figure out if the Devs remembered to include the Cure Magic spell into the cureplayer command. Otherwise, you won't be able to cast directly on your pet.
Your only alternative would be to use the command: useabilityonplayer and I'm pretty sure that only works on pets if they are named differently anyway.
If they did include the new spell, I'm not sure what the argument would be, but most likely it would be:
cureplayer g0 spell pet
That's the one that works for healers at least. You'll have to ask them devs
