Using a modifier will only steal one keybind. Take the following macro:

/cast [mod:alt] !Aspect of the Hawk, [mod:ctrl] !Aspect of the Viper, [mod:shift] !Aspect of the DragonHawk, [mod:alt,shift] !Aspect of the Monkey

Bind it to a key, say "T" for example. Then when you T, it'll look at the combination of the three modifier keys and determine which spell to activate.

For multiple hunters, I recommend using the "!" before the spell name so that if one of your guys is out of sync, it'll activate it on them only if it's not already activated, rather than toggling it off and on.