BEFORE YOU BEGIN: The following procedure requires becoming root to edit a kernel extension. If you didn't understand that last sentence, search Google for more detailed instructions, or ask a geek friend to help. If you hose something, it's not my fault.

1. As root, replace /System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBCDCDriver.kext/Contents/Info.plist with this modified Info.plist (Control-click, then Download Link to Disk). As always, make a backup copy of your original.

   or

   1. As root, edit /System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBCDCDriver.kext/Contents/Info.plist. (As always, make a backup copy first.) It's possible to edit the plist using GUI apps instead of the Terminal.
   2. In the IOKitPersonalities dictionary, add a second entry exactly like the one for AppleUSBCDCDriver, except with a different key name and bDeviceSubClass = 2.

      >               <key>MotorolaPhone</key>
      >               <dict>
      >                       <key>CFBundleIdentifier</key>
      >                       <string>com.apple.driver.AppleUSBCDCDriver</string>
      >                       <key>IOClass</key>
      >                       <string>AppleUSBCDCDriver</string>
      >                       <key>IOProviderClass</key>
      >                       <string>IOUSBDevice</string>
      >                       <key>bDeviceClass</key>
      >                       <integer>2</integer>
      >                       <key>bDeviceProtocol</key>
      >                       <integer>0</integer>
      >                       <key>bDeviceSubClass</key>
      >                       <integer>2</integer>
      >               </dict>
      

2. As root, touch /System/Library/Extensions, and restart. This will cause the modified driver to be seen and loaded.

Technical explanation: Apparently the Motorola V. Series phone is USB CDC ACM compliant, and Mac OS X already has driver for that, so it turns out just to be a driver matching issue. From looking at the USB CDC spec, I'm not sure why Motorola chose bDeviceSubClass = 2, but I don't really understand these things, so... anyway, this seems to work.