Get a wildcard ssl certificate (i.e. with the common name *.yourwebsite.com), assign that wildcard ssl certificate to any website in your IIS, then ran the following commands for each website from C:\Inetpub\AdminScripts:
cscript.exe adsutil.vbs set /w3svc/<site identifier>/SecureBindings ":443:<host header>"
In example, if you wish to publish 3 websites called web, blog and mail identified in IIS as 1, 2 and 3, you have to run the following commands:
cscript.exe adsutil.vbs set /w3svc/1/SecureBindings ":443:web.yourwebsite.com"
cscript.exe adsutil.vbs set /w3svc/2/SecureBindings ":443:blog.yourwebsite.com"
cscript.exe adsutil.vbs set /w3svc/3/SecureBindings ":443:mail.yourwebsite.com"
More infos here.