Adotech, the special developer for this film, is based on phenidone derivate.I believe the oxidation products of this inhibit development and give near normal contrast at the box speed of ISO 20.
With Rodinal the method of controlling the contrast is to greatly overexpose and develop in dilute solution.I did get a result using EI=3 (three) and developing for 15m 68F agitating every 2 min, this in 1:200 dilution.
Using higher EI loses shadow detail.