I do not believe a supervised transfer is available for CUE. You could have the script transfer to the receptionist and have receptionist DN set to forward for no answer and busy to go to an auto attendant script.
http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/cucmac/cuaca/11_0_1/user_guide/eng/CUACA1101CUG_eng.pdf
Go to Options / Preferences
There should be an option for Call Transfers and you can change it to "Perform blind transfer"
