Becuase pots and healthstones are self use only, and smart casting/ smart using was disabled for combat in 2.1, I don't think there is any way other than to bind a key for each toon.

If you have keys that are normally bound to cast healing spells on a particular toon, modify them so that particular toon quaffs a pot or uses a healthstone - use the modifiers shift, ctrl or alt. That might save on using additional keys...

Cheers,
Stealthy