Stop, fix, and wash the paper normally. Exposure time varies widely depending on several factors, such as the type of paper used, the size of the light bulb, and the distance from the paper to the bulb. Experiment or make test strips to determine the reexposure time for a specific print. Try 2 seconds for paper as a starting point. Use a negative with a lot of shadow area or a print with a lot of hightlights for maximum effect, since reexposure affects these areas most.
Sheet films are easier to use for solarization than roll films.
Try enlarging a 35-millimeter negative onto Kodalith film, then making a Kodalith negative, and solarizing that negative during development. The additional advantage to this method is that the original negative remains intact, so if the solarization is not successful, the process can be repeated. Also, this way the original negative can still be used for a normal print, if desired. Underexpose the film or paper slightly prior to reexposure. Alter these figures according to experience.