Howtoforge posted a guide about setting up an SSL Vhost under Apache2 on Ubuntu 9.10/Debian Lenny

This article explains how you can set up an SSL vhost under Apache2 on Ubuntu 9.10 and Debian Lenny so that you can access the vhost over HTTPS (port 443). SSL is short for Secure Sockets Layer and is a cryptographic protocol that provides security for communications over networks by encrypting segments of network connections at the transport layer end-to-end. We use the mod_ssl Apache module here to provide strong cryptography for Apache2 via SSL by the help of the Open Source SSL toolkit OpenSSL.

How To Set Up An SSL Vhost Under Apache2 On Ubuntu 9.10/Debian Lenny