RenderEPS is your best bet as that example works from the source provided on the page. No other dll's needed. It also is small enough to convert to delphi code.
Try to understand what happens in the printbuffer part as that is the basic part of reading the feebdback buffer of what opengl renders on screen, the spewWireFrameEPS does the same except that it formats the output so that it makes an eps file. So try to understand how glFeedbackBuffer(size, GL_3D_COLOR, feedbackBuffer) works and you almost have your solution.