The key is to flash an intermediate ROM that is only 18kb, which seems to get rid of the limitations on upgrading ROMs from different countries.

Found it here. Attached a copy of the intermediate ROM here. Yes. The fake image below is a zip file.

I start with: tl10v100r001chnc00b133

I end up with: TL10V100R001C00B119SP03

I download the international ROM from here