I found and tried Jeff's rules found here but I can't get it to work exactly right:
What I need is to have http://a.b.com go to https://a.b.com (where a is not www, but that distinction shouldn't really affect the rule, should it? www is just another subdomain, right?)
Where Jeff has (.*)billing/(.*), I replaced with (.*), but that's not working.
The results of my attempts produce "redirect loop" errors.
This rewriting stuff is new to me.
Appreciate all your help.