Você precisa criar dois hosts virtuais:
<VirtualHost mysite:80>
<Directory "/Users/myusername/sitefolder">
Options +FollowSymlinks
AllowOverride All
Order Allow,Deny
Allow from all
</Directory>
DocumentRoot "/Users/myusername/sitefolder"
ServerName mysite
</VirtualHost>
<VirtualHost mysite:443>
<Directory "/Users/myusername/sitefolder">
Options +FollowSymlinks
AllowOverride All
Order Allow,Deny
Allow from all
</Directory>
DocumentRoot "/Users/myusername/sitefolder"
ServerName mysite
SSLEngine on
SSLCertificateFile /Users/myusername/certs/server.crt
SSLCertificateKeyFile /Users/myusername/certs/server.key
</VirtualHost>
O primeiro é um host HTTP
regular, enquanto o segundo lida com o tráfego HTTPS
.