Creating a negative image via paper negative

[Gerald C Koch]

There is a technique used to convert an image into a line drawing by sandwiching a positive image and a negative image together and then making a print. Is that what you are trying to do?

[musila]

Also, the psuedo solarization technique might be of interest to you. By turning the lights on for a bit when your paper is in the developer, when the image just comes up. If done right, it reverses the image, with the exceptions of the extreme highlights/shadows, and gives strange effects at the edges of points of contrast.