How to force Multisite to https?

Hi all,

We have a multisite deployment (subfolders) and want to force the whole network onto HTTPS.

In a non-MS deployment you just change the urls in the settings page. But in MS that page isn't the same.

Is there a guide on how to do this as my google-fu kills are failing me on this. Can find plenty for subdomains but not subfolder. Maybe I'm having a bad search day.... :disappointed:

So, any help would be gratefully appreciated.

Thanks
Gavin