This is for hunters / lockz but may work with other classes:
1. logg your main inv some1 and say to them that they should inv your alt when u logg in on him.
2. DONT click Logout just Alt + f4 or Alt + Tab and logg in using other wow (so u have 2 running)
3. logg your alt and get inv kick the guy u inv be4.
4. Run in with your main and clear to the boss u
want an item from.
5.Alt + f4 (or Alt+ Tab and logg in using other wow) take your alt to the boss DONT attack
6. logg your main AGAIN... send pet. now "speedy" logout.
7.logg in on alt your mains pet should still be there and attacking the boss
8. kill the boss you should see him ass gray (attacked by some1 else but this time u will get xp and can loot)
hope u get it
(not good for levling but if u want an item)
And sorry for bad english (Im from SWEDEN)