Switching over an Orion website from http to https is relatively simple. But to have it automagically redirect from http to https is a bit more involved.
1) Orion http to https
a) UPDATE dbo.Websites
b) Create a CSR and have the client provide the certificate
c) Install the certificate
d) stop the default site (also change the binding to 8080 - just to be safe). create bindings for Orion for https using the imported certificate
2) http to https redirection using URL Rewrite
a) install URL rewrite for IIS and add a rule for redirection.
b) Configure rule
One thing I have noticed is that if you're using additional web servers behind a load balancer - google maps may not work properly. You will have to rewrite the google maps code to use https.