Original post is here, though it's lacking in detail.
http://www.ownedcore.com/forums/world-o ... -back.html
Basically:
1. Have someone with the item mog you want.
2. Run a dungeon with them, DF or not. Get the item to drop that matches the mog reqs (1H sword to 1H sword mog you want, etc.). Has to be rare or epic, greens can't be traded cross-server.
3. Have them take the drop and transmogrify it. Make sure they do NOT unequip it.
4. Have them trade it back, taking it from their equipped slot straight to the trade window. In the trade window it WILL NOT show the transmog and will say 0/0 durability. You keep the look! The script to trade between servers overrides what would normally make the item soulbound and untradeable when mogged.
Restrictions:
- YOUR TOON MUST BE FROM A DIFFERENT SERVER THAN THE PERSON MAKING OR RECEIVING THE MOG. It will not work for same-server transfers.
- The mog must be of something you are able to equip. Say, you want a Cruel Barb from Deadmines normal to look like Quel'Delar. You have to be 80+ for the mog to stick, or it won't keep in the trade, because you need to be 80 to equip Quel.
- Like the above, you can't mog Immolation plate for a DK, no class restricted ones will work for other classes. You could mog Immolation for a pally that didn't have the set, though.
But! This is a great way to gift and get retired looks, like the Corrupted Ashbringer and Rhok and such. Happy gifting!