I searched, but i couldn't find anything simular to this
when you are in an area where you have to kill fx a named mob, log into an alt, and invite someone to group and give him leader. Exit wow with alt + f4 and log in on your main. Ask the guy from before to invite you to the group and give you leader, now you can kick him from the group.
Now you will be in group with you alt which is showed as disconnected.
Now you can run around using /target to find the named mob, and because your in group with your alt you can now put a raid mark on it. This way you can easily detect the mob, even through walls and hills.