Windows 8 Modern UI Apps deployment without store

Windows 8 Modern UI Apps deployment without store

We want to build a windows 8 application for a customer. It's an
application which shall be used internally only. I think a good
interpretation of "internally only" in this case is:
shall be used only by employees
shall be used on devices the employee has (corporate and private devices)
Point 1. is already taken care of, as we have some authentification
mechanism bound to a central application rights server inside the app.
Point 2. won't be a big problem we thought. But when testing the
deployment I came accross some restrictions. And I'm getting confused more
and more by every information I read about it. Let's see what I've got
already (may be wrong and incomplete):
You can install W8 Apps by sideloading
Sideloading requires a developer licence OR
Sideloading requires the PC to be in a domain
A developer license requires a MS Account
Being in a domain requires Windows 8 Enterprise, Pro or RT
If you have Pro or RT, you also need a sideloading product activation key
(where to get that from?)
So, conclusion: You can't install you own app on devices which are not
part of your domain, without violating MS developer license restrictions.
Is this all correct?
If so, I have another question: How does Google Chrome do this? After
installing the desktop app you can switch it to a metro app?
Thanks in advance for your help!