It looks like this can be acheived using the moto4lin package

Nicely described on this site:

http://3dgo.net/2007/12/17/ubuntu-motorola-pebl-u6/

I have tested it by downloading a photo from the phone, but I’m not sure it has all the features of the windows app.   I wonder if it would allow me to use the phone as a modem, or send texts using the PC keyboard.   Not that I’ve ever used those features.