I'm very interested in this as well for making enlarged positives from separation negatives.
By the way, here is what the freestyle page says...
Continuous-tone results can be achieved by using a dilute working solution of standard paper developer. Dektol 1:7 or 1:9 is a popular dilution to achieve continuous tone results. Ethol LPD, Agfa Neutol, Clayton Extend Plus, Clayton P-20, Nacco Printol, or any of our Arista and Arista Premium Paper Developers are also recommended. Your individual optimal dilution and developing time will vary based on your desired results.