here are the official rules
"Elite Upgrade Terms
OnePass Elite upgrades are valid for travel within or between the 48 contiguous U.S., Alaska, Canada, Mexico, the Caribbean and Central and South America. Elite upgrades are also available on select flights within or between the Mid Pacific and Asia. Continental Airlines flights with a BusinessFirst cabin, including transatlantic and transpacific flights, flights to/from Central and South America, or within and between Hawaii, the Mid Pacific and Asia are not eligible for Elite upgrades. To receive a BusinessFirst upgrade, OnePass members may use miles."