Motorola doesn't seem to provide any Linux support and their support pages are virtually un-navigable.
Have you tried connecting it up and then running dmesg in a terminal?
Dmesg produces a lot of output, so you might want to pipe it to a file (something like this
so you can then open the file and search for any references to the phone. This will tell you whether the computer is actually seeing the device.
If it is, post the portion of the output relating to the phone back here, being sure to surround it with "code" tags, which become available when you click the "Go Advanced" button at the bottom of the quick reply window.