On page 82 it mentions connecting to a computer using a powered usb port. It also mentions having the right cable.
No mention of any software to load which is a bit strange.
I can't find any mention of connection sharing.
I did see this:
"and supporting software are sold separately"
I would talk to the folks who sold you the phone.
I played with my motorola W285 and Vista installed it as a modem. This indicates to me you could possibly use it as a dialup. At 28K its not something I will be doing any time soon.