Access to exchange online from partner center

[JayJamieson]

Are there any samples to accessing Exchange online from partner center?

What i want to be able to do is get a list of all mailboxes and shared mailboxes for a given client. I've looked at the examples/api reference and couldn't find anything that does this.

Ive seen examples in the powershell module that lets you do this here however this is not documented for the rest api.