When you start up the phone without a sim card, it goes into a  locked screen that says "no sim card found", and you can't even get into  the registration app. So the first step is to get around that screen.  You have to connect to your phone with adb shell and get root access,  and then type the following command:
sqlite3  /data/data/com.android.providers.settings/databases/settings.db  "INSERT INTO system (name, value) VALUES ('device_provisioned', 1);"

And  then reboot the phone. When it starts up again it will go into the  registration screen instead of the locked "no sim card" screen.

This  assumes that you have the sqlite3 binary on your phone. This binary is  provided in RC30 v1.2. Alternatively, you could manually copy the binary  to your phone with adb push, or put it on the sdcard and copy it to  your phone. I can post a copy of just the sqlite3 binary if needed.

The second step is to enable and configure wifi, so that the  registration process can connect to the google servers. In an adb shell  session, type the following command:

am start -a  android.intent.action.MAIN -n com.android.settings/.Settings

This  doesn't have to have root access to work. It works fine with the  "shell" user that adb on non-modded phones runs as.

That command  will bring up the settings page on your phone. From there, you can  enable wifi and connect to your wifi network, and then proceed with  registration as per normal