what you are trying to do will result in the same thinking as:
"I want my healer to heal a target that i'm mouseovering"

basically, I think (i'm not versed in LUA code, but seeing one can relay whispers with it, one can also get other commands) it could be lua scripted if you make a macro on your main:
/focus
/whisper toons "%n"

and on the toons a lua script doing
get "name" from whisper
do /target "name"


but that'll be on the very edge of automation, and it will indeed only skip you that quarter to half a second. I don't know if it's worth the hastle if you suddenly get 4 to 5 accs banned because of automation.