what exactly did you add in the way of code? The errors you are having sound more like the port is busy.
First, I made a copy of the AnalogInput example.
Then, I added Serial.print( val ) right after the first digitalWrite(ledPin, HIGH).
I was trying to get the MotorKnob example to work, and was verifying that
I could even get some analog input.
Yes, it looks to me like the port os busy. But I've rebooted both Mac and Arduino, and deleted
the /dev/tty.*ARD* goodie, and deleted the Arduino from the list of bluetooth devices.
Seems like either one of them should've let go of the port by now.