CO does not offer free international upgrades.
UA does not either...however, operational upgrades are at least "heard of" in UA.

No free upgrades on partner airlines.
Some CO elites have reported getting upgraded on US Air though in domestic US flights.

There is a program called "star alliance upgrade awards" where you can buy a high-fare (e.g., Y/B) on a participating airline and upgrade with miles using your Star-airline's miles.
There are strict rules for these upgrades. And the high-fares are pretty high!