I am not sure on the post 5.9 Cummins....
I do know on the 6.0+ PSD you really shouldn't use any alternate fuel, it can/will harm the injectors. Plus with the computer controls, very much non-diesel, like more that 15% can cause running issues, the combustion process is not putting off what the computer is expecting, and can throw it into a tizzy......
So, to answer your question, CAN you run Wxx in that era Cummins, probably. SHOULD you, no. I know in my case, with a 6.0 and the low percentage of waste that it could run safely, it would take a long time to pay for a set of injectors....... I have not had a chance to t-shoot mine, but I believe I may have caused an injector issue with a tank of questionable #2 from a pump...... would not take the chance with running waste anything in it.....