ldd gives you the dynamic libraries that a file depends on.
$ ldd binaryfile
nm gives you the list of symbols in the file. Functions that are exported by the library will be present as symbols. Many files are stripped of symbols before they are released, though.
$ nm binaryfile/libraryfile
On many *NIX variants, you can set a dynamic library of your choice to be searched first when dynamic library calls are made.
Take an executable and determine its dependencies. View the symbols in those library-files. Make your own library-file with implementations for the symbols that seem to be of relevance to you. Set the LD_PRELOAD variable to the name of your library file. Run the executable.