Dont know if this is relevant any more, but i'll add my solution to this question.
First, go to the directory for the httpd.conf templates:
cd /etc/e-smith/templates/etc/httpd/conf/httpd.conf
Then edit the file 80VirtualHosts
pico 80VirtualHosts
At the end of that file, after the last }, add this:
-----snip------
<VirtualHost 0.0.0.0:80>
ServerName webmail.example.com
DocumentRoot /home/httpd/html/horde/imp
Alias /horde /home/httpd/html/horde
RewriteEngine on
RewriteCond %\{SERVER_PORT\} !^443$
RewriteRule ^.*$
https://%\{HTTP_HOST\}$1 [L,R]
</VirtualHost>
<VirtualHost 0.0.0.0:443>
SSLEngine on
ServerName webmail.example.com
DocumentRoot /home/httpd/html/horde/imp
Alias /horde /home/httpd/html/horde
</VirtualHost>
-----snip-----
This will enable webmail.example.com as a virtual host. The alias is needed to find all graphics, templates and other stuff. Also, by adding one vhost for port 80 with rewrite rules to port 443 and one vhost for port 443, webmail.example.com will allways be https.
Note the \ before the brackets in the rewrite rules. These hare neccessary, or else the scripts for expanding the template will fail to parse the brackets.
After you've done this, simply issue:
signal-event email-update
or
expand-template /etc/httpd/conf/httpd.conf
/etc/init.d/httpd-admin restart
Witch will reconfigure some stuff, including expanding the httpd.conf file and restart the webserver i think. (seems to work anyway).
Test.