Just remove the words "SerialPort" :-) ours is just BluetoothListener. Have a read of the user guide at http://www.alanjmcf.me.uk/comms/bluetooth/32feet.NET%20--%20User%20Guide.html e.g.
...
Dim lsnr As New BluetoothListener(MyConsts.MyServiceUuid)
lsnr.Start()
' Now accept new connections, perhaps using the thread pool to handle each
Dim conn As New BluetoothClient = lsnr.AcceptBluetoothClient()
Dim peerStream As Stream = conn.GetStream()
...
One can set the ServiceName property or even supply a full custom service record to the constructor. (The IO and threading model is .NET's, so its not like the Blackberry API where one adds that interface BluetoothSerialPortListener to one of the application's classes, but background/asynchronous forms are available).