i am afraid this will be near impossible: windows SDK, CVI library and C runtime are quite different beast. unless you know the internals of the last 2 libraries, there is no way to be certain that nothing will break. and if you find a solution now, there is absolutely no warranty that it will be portable and will not break later, at the next release of the compiler for example.
that's exactly why i always thought the C stdio library is flawed: there is absolutely no way to extend its functionalities. the FILE type is opaque with no documented low-level interface. if you want to add a new file type (like being able to use standard output functions on a com port) you have to write a wrapper around the C library and use this wrapper everywhere instead of the standard calls. (i wrote one once, that i since use every time i envision that i will have to perform i/o on different kind of peripherals).
i don't know if anybody here knows Ada (the programming language), but its streaming library is the best i have ever seen: complete, well-defined (including error codes), user extendable, with a clear separation between formatting and input/output... it is exactly what every streaming library should be.
