This short how-to explains how to get HTTPS/SSL working on Leopard, which uses apache2. First, follow the steps in this hint, but instead of following Step 5, do the following:
Edit /private/etc/apache2/httpd.conf, and uncomment the following line (it’s line 473 in my installation):
Modify as necessary for macports conf/certs
This page Using mod_ssl on Mac OS X is also quite good, useful, handy, whatever.