365, Sharepoint add new site collection admin to all users for onedrive access?

At the moment, if you go into a users sharepoint profile in manage profiles and select site administrations permissions, I am manually adding a IT security group in so we (IT) can have access to their onedrives etc eg:

I want to know, how can I push out the IT Security Group like as aboves example to all users in one go. Powershell?

And if so, can I set this as default instead of keep having to do it when I get a new user?

Thanks