How can I obtain a computer readable model of Dr. Gerhard Michal's biological pathways map?
Roche's Biochemical Pathways works as a big png image and just put labels on the map. But you could try to extract data using queries like http://biochemical-pathways.com/pol/fts/query?query=Glutarate
It seems to be legal as it's not prohibited.

Escher is a good pathway visualization tool where you can save map in JSON or SVG.

Another choice is VMH (Virtual Metabolic Human) - the virtual metabolic human database provides literature-derived information on human metabolism, gut microbial metabolism, nutrition, and diseases.

Reactome has two layer map - first layer is biological interactions, second layer is pathways.