I'm not sure if this works, someone try it. I just had this idea when I loaned my account for my friend to farm some gold.
This is just to get login details. Just sel all the gear, send gold to your char and use some old hack to ban the account.
So:
Tell him that you are now gonna pay and tell him to change the pasword to "password12345" or something. Then wait a while and try to log in. I think that someone might allready change the pass while you are "paying".
Just an idea I got as tired. I think this has pretty low succes prosent. But I think I'll try it out..