1. Introduce it to the code base (tell it: we're going to work on this project, project does X is written in language Y). Ask it to look at the project to familiarize.

2. Tell it you want to refactor the code to achieve goal Z. Tell it to take a look and tell you how it will approach this. Consider showing it one example refactor you've already done (before and after).

3. Ask it to refactor one thing (only) and let you look at what it did.

4. Course correct if it didn't do the right thing.

5 Repeat.