You can do this using PdaNet .

You can do this using PdaNet. From KnowYourMobile.com: To use your Milestone as a mobile broadband dongle, you will need: Motorola Milestone USB Drivers PDANet Tethering Software ($15.95 to buy right now, limited trial also available) Step I: Tap the upward pointing arrow on the Milestone's home screen to get to the app menu Tap the Settings icon Tap Applications Tap Development Check the box for USB debugging Step II: Install the PDANet software on both your PC and Milestone -- when installed on the desktop, it should automatically install the USB driver for you but if it doesn’t, you will have to use the driver you downloaded above. Connect your Milestone to your PC via USB, then launch PDANet on your device Click on "Turn PdaNet On" on the Milestone Right-click the PDANet icon in the taskbar on your PC, then click Connect