Here's the changes for Sprint
Pocket PC
1. No matter what application you're in, open the Start Menu and select Settings.
2. At the bottom of the resulting screen will be a tab labeled "Connections." Select it.
3. Tap on the Connections icon near the top of the screen.
4. Select the link labeled "Manage existing connections."
5. You'll see a list of possible connection methods. (For many people there'll only be one.) Select whichever of these is your primary connection, then tap on the "Edit..." button near the bottom of the page.
6. Starting on the next page, hit the Next button twice.
7. You should be on a page with a button labeled "Advanced." Tap on it.
8. At the bottom of the resulting screen will be a tab labeled "Servers." Select it.
9. Hit the radio button for "Use specific server addresses."
10. Below that will be text boxes where you can enter the addresses you want to use. Change DNS to "4.2.2.1" and change Alt DNS to "4.2.2.2"
11. Click OK and then hit the Finish button.
This isn't mine, it came from here:
Here