Here is a USB tethering tutorial I wrote up.
Merry X-Mas
First visit the
http://www.vzam.net/site click on download now.
Then use these settings to download your copy of VZAccess Manager:

Enter your phone number or any number for that matter and hit continue.

You will be prompted with this screen and just hit download.

On your BlackBerry Storm Hit the BB Key...go to Options...Memory and make sure you have your setting like this:

Hit the BB Key and save.
After its downloaded install it and run it.

From here on, just follow the on screen instructions:

On this step you won't see anything in this screen, I just have that because i've already run the setup.