You could technically just write out the declarations from the header file manually, but all in all, I wouldn't recommend that. Headers are written the way they are to include the functionality they need. To pick and choose what to keep sounds a little odd. Someone -- I believe it was brewbuck -- likend header files to menus at restaurants. You shouldn't really need to edit the menu or rewrite your own.
Are you sure you know what you're doing? This doesn't make sense if you are going to statically link to a library that has the implementation of one function that you need.