[HOpenGL] Getting GLU entry points at runtime

Does anybody know if there is way to get the proc addresses for gluUnProject4 gluBuild3DMipmaps dynamically i.e. at runtime? They appeared in GLU 1.3, WinDoze comes with GLU 1.2, and glXGetProcAddress seems to be agnostic about GLU functions (probably wglGetProcAddress behaves similarly). So I'm a bit stuck here... :-( Cheers, S.