Using char16_t, char32_t etc without C++ 11?

I would like to have fixed width types including character types. stdint.h provides types for integers, but not characters, unless when using C++11, which i can't do.

Is their a clean way to define these types (char16_t, char32_t, etc) without conflicting with those defined by C++11 in case the source would ever be mixed with C++11 ?

Thank you :)