Hi Hodgdon,
I was struggling with the exact same problem since 2 weeks, but found a way to update my CDE133BT this morning.
Using a MBP mid2009, the file always stopped transferring after 453 kb both in bootcamp win7 (where I could not download the BT drivers anyways) and in Mountain Lion.
So I followed instruction given by alpine until the pairing process. Then I put the MBP into visible mode in bluetooth preference, in Moutain Lion, and tried to connect through the alpine. When 'Alpine CD reveiver" appear on the list of BT devices in BT menu, I added the port "OBEX Object Push" using the wheel on the bottom, then did "update device" (same wheel). The Alpine should then be able to connect to the computer (maybe need to restart once using the car key).
Here is the trick : before, when I used to put the receiver on "FW Update" on "Yes" and "Waiting" appeared, the bluetooth logo on the receiver was always disappearing (the alpine disconnects by itself after a short period of time). Browsing the device directory from the computer in facts does not wake up the connection.
So I checked "use as audio device" option in the bluetooth menu on the Macbook menu bar.
When in "Waiting" mode, I launched some music on Itunes: then only did the computer connect to the receiver, and music started to play through the car audio. Doing this, the BT logo appears on the receiver and blinks while in "Waiting" mode.
I then quickly stopped the music and dragged the file in the update folder using "browse device". tranfer took less than 10 sec.
I had to try 5 times. 4 times the alpine stayed stuck on "Update please don't touch any button" for too long. last time it worked.
Hope it helps, (that update process was driving me mad).