You will need a fast method to force disconnection from the server, like killing a proxy connection or alt+F4 while keeping two instances of WoW running at the same time.
First, just to make sure, test if the trick is happening on your realm. I don't know if this is cause by latency or region, so, it's better test it first.
Put two of your characters (A and B) at the same place, where A can target B. Kill the connection or close the game (don't use "logout" or "exit game" options) and quickly login the other character. If you can see the other one still online (but client-orphan), then the trick works. You can use /dance on A and when you log in B, A will still be dancing.
If it worked, move A, B and other of your characters to Timeless Isle and put all of them at a remote location. The underwater cave below the frog zone, a high pillar or a fatigue region are good places. If you are going to farm blood coins with A, use the censer on A and log in other characters. Before change characters, let B naked and PvP flagged. They need to be naked due to the high PvP resilience. If you don't kill your alts fast, they disappear ~30 seconds after the disconnection.
It is not a fast way to get blood coins, but at least you won't need another players or multiple accounts.
You can use this trick to do other fun things, like coping an alt visual or having a rogue pickpocket (glyphed) a mogu or mantid and then copy its appearance.