As the originator of the HC-110 monobath you pointed to, I can make some suggestions on using Rodinal in a similar manner.
If you're willing to use Rodinal at 1:25 or maybe even less dilution (1:15?) you could probably make a conventional monobath simply by adding 30-40 g/L of sodium thiosulfate crystals. The trick would be finding the right combination of Rodinal dilution, temperature, and agitation. A low concentration conventional fixer will take 4-5 minutes to clear the film, so your development should be at normal contrast in no more than that four minute minimum.
Given that (as has been codified for Df96) temperature is the primary control on development, and agitation controls fixing, you could probably get close for a start with Rodinal 1:25 at 80F and minimal agitation, every second or third minute (that would be one agitation cycle after filling the tank and one at halfway through a six minute process cycle).
Start with a clearing test; your final process time will be twice that figure (and won't need to account for exhaustion, as this will be a one-shot monobath). Pick a temperature that will give you normal development in no more than 2/3 of that clearing time in 1:25, shoot a test roll, and try it. You may find you have to adjust your temperature or agitation for different films -- or you might not; Df96 has only a couple films that need different processing.
