How do I get it working with Big Commerce?
Yes! By default Big Commerce doesn't immediately make available on the site's pages the information for the Magic Edit to fully function. But by simply adding a small script block in your store's templates, it will gain all the needed functionality
Copy and Paste the below code snippet into your Theme's base Template, just above the closing body tag, so it is present on all pages of your store.
For most themes, the Base template can be found in the Theme files at templates/layout/base.html.