Samsung Delve SCH-R800 Tethering For Data Guide (Alltel)
I'm on Alltel, so your mileage may vary...
Simply download JavaInstall.rar, extract it, and then extract and install the driver with your phone unplugged.
Plug in the phone once the driver is installed, and let windows install the phone. Then, open the network settings area and create a new connection. Choose connect to the internet and dialup connection, and then the manual setup option.
The user and pass can be empty, but you can use "email@example.com" and pass "alltel" and the phone number should be *99# for 1x mode or #777 for broadband mode.