For anyone playing mages that may be trying the same thing, the suggestion from Ugmahedhurtz works great for Counterspell. Now I use:

#showtooltip Counterspell
/stopcasting
/target focus
/assist focus
/castsequence reset=24 Counterspell,,,


& it works like a charm (each mage would get a different last line, as outlined above). Bottom line, is this works when some of the other solutions didnt quite work with the cast sequence deal.

On my main (who doesnt have a silence) If I notice someone that needs to be "SHUT UP" I just target them & the hotkey once.

Between this & the Blood elf racial, I tend to keep healers quite frustrated.