how do you get them

You need the ring of visibility from the Desert Treasure quest. Then, go to the elf's tomb near the Dwarf Cannon place and talk to the ghost there. He starts you out on the mini-quest.

You'll need 53 thieving to get them, an amulet of ghostspeak and the ring of visibility from Desert Treasures quest (requires 53 thieving). After you've got them the guide from tip.it will show you all the precise locations -

 

 

 

 

 

 

 

http://tip.it/runescape/?page=ghostly_robes.htm

 

 

 

 

 

 

 

;)

thanks