Restoring LG Optimus 2X P990 back to stock LG software

I have flashed a lot of custom ROMs onto my phone, like CM7, kangs and such of CM9 before it's released, MIUI, and so on. I didn't want to wait till the third quarter of 2012 before I got some IC on my phone. Now that we're almost that far into 2012, I was wondering how I could restore my phone back to LG's stock Gingerbread software - the one that i had before I flashed CM7 - and unroot my phone. I have lost my backup so I cant restore. I'll have to use smart or NVFlash or something like that. How can I restore my LG Optimus 2X P990 back to original LG software, so that I am ready for updating it to LG's ICS release?