Originally Posted by Bladewire

See if this works

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

RewriteCond %{SERVER_PORT} !^443$
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]