Generate java classes programmatically without mps ide

I'm a bloody beginner, maybe my approach is totally wrong.

Based on the mps-calculator-language-tutorial. How can I generate the output java class just-in-time? i.e. we have my dsl input:

calculator MySalary 
input Java Hours 
input PHP Hours 
 
output Java Hours * 10 + PHP Hours * 5

I'm working with the mps-ide which is able to generate java classes, these I can add to the source path to intellij for my application. But whats happened if I want to integrate external scripts based on my gramma?

What I imagine is I getting an artifact from mps to load these scripts or something similar. Which generate these java classes to integrate to my application on the fly.

Is it understandable?