I think I figured it out (atleast it seems to work for me).
Under HKLM\Software\OEM\PhoneSetting
Change AllowRoaming to 0 (not sure if this is needed or not)
Under HKLM\Software\OEM\PhoneSetting\NetworkService
Change ItemCount to 3 (instead of 2)
Create a new String called ItemName3 with the value of "Roam Only" (without quotes)
Create a new DWord called ItemValue3 with a value of 3
You don't even have to soft reset. You can go into your phone settings and now have the option of Roam Only and when you select it you get the little triangle for roaming.
See this post for the workaround on getting the settings to stick after a soft reset:
http://forum.ppcgeeks.com/showpost.p...60&postcount=9