I've tried both methods and both worked for me. You just have to watch your data usage. If you use this as the primary source of your internet connection then they will catch on because they monitor the usage. But if you just use it for here and there while you're on the road then it will be ok. But because it's a PDA phone they will charge you $45/month for unlimited data. If you use a regular phone to do this with then unlimited VCAST will be $15/month. I've had PDA/Smart phones for ever I couldn't go back to a regular phone.
Bluetooth
http://www.hellomotoq.com/forums/front-page-content/4-motorola-q-dial-up-networking-dun-pc-mac-via-bluetooth.html
USB
http://www.hellomotoq.com/forums/front-page-content/121-motorola-q-dial-up-networking-dun-pc-via-usb-cable.html