you might want to go for a key modifier option then... I am not sure what category a pollied mob comes under regarding harm.

how about

Code:
/cast [target=focus,harm,mod:shift] counterspell
/stopmacro [nomod]
/assist main
/castsequence reset=15 counterspell,,
this way if you cans the macro with shift pressed it will CS your focus and stop otherwise it will assist your main and cast counterspell on yoru target