Generally application DLLs are placed in either application' current directory or in one of standard directories (which are part of %PATH% ).

In case you absulutely need this, other than appending one more string to PATH variable, you can try dynamic loading of your DLL. For this you need to call LoadLibrary, and pass absolute or relative path of DLL location.

Dynamic loading has its own implications. It should be used only when specific functionality is needed at later time of execution. For instance backup program or a game utility within your application.