Reeder and Hinkel describe a fairly easy process for producing curves for any process, equipment, and paper in their book "Digital Negatives." It uses standard Photoshop tools and is self compensating for different printers and materials. Burkholder also describes the process, in a somewhat more complicated way, in his "Making Digital Negatives for Contact Printing." He also gives some quite usable curves for popular processes.

Basically, you first make a test strip through your negative material to determine the exposure needed for D-Max. Then you print a step tablet on your negative material and print it using the exposure you determined. Then you measure the densities of the steps on the print and derive the curve.