We have no tutorials at the moment I'm afraid. Once you have your materialx file (.mtlx) and your geometry imported (e.g. Alembic), then you can create an operator network from Render Settings > Advanced and create a materialx operator, setting the path to the mtlx and specifying the look.
I'm not sure how can your write out an mtlx file, maybe there are some tools in Maya. It's certainly not possible in C4D at the moment.
