While importing a placeholder for some iPads into Profile Manager I was peeking through profilemanager.log, when I found this gem.
 [2014/05/22 16:17:21.942] I: Imported placeholder device "MH-Gary Ho_iPad Mini45", SerialNumber=F7NMXXXXXX84, IMEI=, MEID=, UDID=, DeviceID=, AirplayPassword=
What I did next was add a new column AirplayPassword= to the placeholder CSV file and put a password in. I then uploaded the placeholder for an AppleTV and it added the Airplay password to my AppleTV Device in ProfileManager.
Just yesterday I added 20 AppleTVs to Profile Manager, I could have saved a few steps with this hint.[crarko adds: If you don’t know about Apple Profile Manager for OS X Server …