I want to flash India ROM on my AT&T Lumia 920. Is the old guide still valid?

[Windows Central Question]

Is this guide still valid: http://forums.windowscentral.com/nokia-lumia-920/239797-8.htm

Or is there a new/better way to do this?

Note: I currently have preview for developers installed.

I'm having weird issues like camera not working, sensor not working, etc. I would do a hard reset, but I thought that now that I'm doing a hard reset, might as well unbrand it