Could implementing it as a widget solve your problem?
If you do it as an Opera Widget, it will work as an app on most phones. Opera Mobile 10 should work on Win Mob 6.0 I think.
Opera Widgets SDK
Access your phone's camera with WAC widgets
Have no clue as of how to do it, but the example given in the second link seems to be the one for you. It is developed for Android, but should work everywhere where Opera Mobile (>= 9.5) runs.