Toran Proxy for wpackagist

I’ve just spent 40 minutes trying to find an answer to this, but I’ve had no luck so far.

Is it possible to proxy wpackagist through Toran Proxy?

Every example composer.json file I’ve seen online (forum threads, github repos, blog posts) seem to just pull directly from wpackagist before falling back to Toran Proxy. I don’t want this, I want all my WP plugins to be pulled from Toran Proxy so we can cache them for performance reasons.

I’ve tried everything I can think of in my composer.json file to get it working, but all I get are errors, such as:
The requested package wpackagist-plugin/wordfence could not be found in any version

If it is possible, does anyone know how? Do I need to add wpackagist to Toran Proxy somewhere? According to another thread on here “yes it proxies wpackagist”: Toran Proxy

If this information is incorrect, I’ll need to find another solution.

Edit: I’m beginning to think this isn’t possible, ‘packagist.org’ is hardcoded all the way through Toran Proxy, I don’t think you can add wpackagist anywhere. I could be wrong though.

I’m thinking it’s not possible either. Toran only mentions Packagist and GitHub.