Originally Posted by
Kebero Any info on flashing this ROM to an ATT branded, Portico 920?
you flash it the same way it has been described in Laura's link above. Once you are at the step in his tutorial to do OTA updates on the pre-portico Rogers you can then flash the ATT Dev rom. However, S
nickler from xda has flashed this to his Lumia 920 and experienced stability issues (see his post#169 in same thread). He writes that since he is on the Rogers flashed rom (Amber) he has not experienced the same issues.
your options are
summarized in my post here in the same thread that Laura posted. In any of these cases you first have to flash the pre-portico Rogers. Once you update to Amber either on Rogers, French or ATT Dev rom you cannot go back to stock ATT - at least not at the time that I am writing this.