Does anyone know if the standard fit VW GAMMA head unit will accept the speaker output of a hands-free car kit ?

I know the MUTE line input can be used to mute the radio/CD but not sure if this head unit will allow direct play through the car speakers with out the neex for a specialist lead (like the ones Sio Communications) sell that have a multi-way change over relay.
Any clues would be helpful, as the readymade kits from SC are £60 +p&p for the Motorola Bluetooth car kits.
Thanks
Paul