Even Easier TLS
Actually, there is now an easier way. Google supports TLS for personal domains in beta. But you can get it to work on the mainstream side by first going to draft.blogger.com, making the TLS change there--along with your 3rd-party domain name change--and then wait a few minutes. Now go back to your regular www.blogger.com page and you will see TLS is now supported. There's apparently a problem with getting a browser warning if you use mixed content (encrypted and unencrypted) but I haven't encountered that problem, since I'm not pulling in any unencrypted links.