Setting up HTTPs / SSL on a Multisite Setup

Hi there,

I'm looking to move my multisite setup over to HTTPS.

I'm on a sub-directory setup, so no sub-domain issues, but I've discovered that it's not as simple as changing the site URL, as it is with non-multisite. I can't find any good information on how to do this with Multisite, so would appreciate any pointers on where I have to change the URLS.

Also, I was wondering if it's possible to have HTTPs on some sub-sites and not others?

Also, I'm running the domain mapping plugin and have one domain mapped into this site. Will this affect it? I do not need that domain to run on SSL/HTTPs so if I can exclude it then that's fine.

Thanks for any help