in keyclone you should be able to make a keymap with a hotstring like:

paladin.kcl
--
1 heal_hunter

(you have a wow macro tied to some key... '1' in this case.. test it by hitting '1' from within the paladin screen and seeing the paladin heal the hunter)

hunter.kcl
--
shift-F1 heal_hunter

load the appropriate keymap to the appropriate wow clone

at which point, if you are active on the hunter clone, hitting shift-F1 (or whatever key you want to map) will be translated to a hotstring... and sent to the paladin... no other actions should be taken by the hunter.

The paladin will then translate 'heal_hunter' back into the '1' key, which is tied to a wow macro '/cast heal <leader>' (or whatever that wow macro is)

if that doesn't work, please let me know (it is one of the core functionalities...)