Here's a quick tutorial on how to set set project environment variables. I tend to do this at the beginning of the project and use the .bat as a launcher whenever I need to open a file for that certain project.
Here is a link to some variables. There are many more undocumented variables
Here are the common ones I use for Mari
This sets the config.ocio
This one changes the cache so you wont be working out of your documents but instead out of a folder in the project location