How to link vagrant + bem (project-stub) + modx + gitify into a single system with the ability to maintain the project normally?

Question

MODX

I am still new to BEM and it is not very clear how to implement BEM in CMS.
I want something like this:
- set up vagrant
- installed project-stub
- made layout of the site
- installed modx
- somehow integrated the layout into modx (for example, gitify or other methods)
- set up deployment to the production server
When changing some block ( component) of the layout, all code must be processed by postcss, compressed, etc.