I started using x-ray dupe for making enlarged negs a while ago and still fine tuning it. I've been using Fuji Mi-Dup
As this film needs a lot of exposure and strong developer (I'm using almost straight stock dektol), I'm finding that starting with a contrasty negative is easier; otherwise I'm thinking it would be hard to build up the contrast from a 'normal' negative.
I have been using RC paper to do test contact prints from the test enlarged negs. Printing them using a Grade 0 filter. That aproximates how contrasty the negative should be for most alt processes (at least the iron ones- I'm not sure about albumen).
So, starting with a high contrast original and then fine tuning the enlarged negative has been working with me.