After a bit of tinkering, I managed to provision my ADP1 setup without a SIM card.  A bit of google, and here is what I did:

  1. Download the Android SDK.  In my case, I unzipped it to C:\android-sdk-windows-1.1_r1.
  2. Connection the phone via the USB cable to my computer.  When the phone asks for a device.
  3. You'll get the new hardware dialog, when prompted for the drivers, you'll need to specify the location.  The Android SDK has the drivers, in my case they were at C:\android-sdk-windows-1.1_r1\usb_driver\x86.
  4. Once you have the drivers installed cd to c:\android-sdk-windows-1.1_r1\tools.
  5. Type adb devices.  This should list all the Android devices that you have connected.  If you don't see any devices listed, then you have a problem.
  6. Type adb shell.  This will direct your commands to your ADP1
  7. Now while at the adb shell, su to root, then : 
  8. cd /data/data/com.android/providers.settings/databases/
  9. sqlite3 settings.db
  10. INSERT INTO system (name, value) VALUES ('device_provisioned', 1);
  11. .quit
  12. Reboot the phone
  13. adb shell
  14. am start -a android.intent.action.MAIN -n com.android.settings/.Settings

Once all that is done, you should be enable to use your ADP1 as if you had a SIM card in it (we'll except for the phoning part).

Useful link:  FAQ: Unlocking/Activating a G1 or ADP1 Without A Sim Card.