[Lopan]

You may be encountering the same problem I had with my Sprint Touch Diamond intially.
If you find that the Second drop down menu is missing from "Internet Sharing", then do this: (if its there though, don't bother doing this)
1. Delete this registry entry HKLM\Comm\InternetSharing\Settings\ForceCellConnec tion (it's ForceCell"Something" you'll recognize it)
2. Soft reset your phone
3. Open Internet Sharing again, make sure you now have your second Internet Sharing drop down menu option.

If your ForceCellConnection registry entry pointed to something other than the name of your current Cellular Data connection in the "Manage My Connections" menu, then USB tethering and/or Wifi Router wont work, at least it wouldn't for me.

With the second drop down option available you will be able to choose from a valid Connection to use for Internet sharing that will allow you to use your $15/Month Sprint PCS service with the phone connected directly with a USB cable and/or with WifiRouter Wirelessly

If you need a Registry editor, I recommend using Total Commander (Free) to edit your registry directly on your phone.

I hope thats what you were asking about. If not, then just forget I even brought the whole thing up.