I would like to have Tomcat handle the https requests for that subdomain. I don't think this forwarding technique can work in this case. How do I set that up so that Tomcat receives the requests on port 443 while apache handles port 80.
Na verdade, você pode configurar hosts virtuais para encaminhar todos os tipos de solicitações, incluindo 443. Basta configurar dois hosts virtuais para o mesmo servidor, mas encaminhar por porta. A porta 80 pode ir para o seu webhost e 443 para o seu tomcate via ajp ou proxy http. Exemplo:
NameVirtualHost *:80
<VirtualHost *:80>
ServerAdmin webmaster@localhost
ServerName proctinator.com
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [R,L]
DocumentRoot /var/www
<Directory />
Options FollowSymLinks
AllowOverride None
</Directory>
<Directory /var/www/>
Options Indexes FollowSymLinks MultiViews
AllowOverride all
Order allow,deny
allow from all
</Directory>
ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
<Directory "/usr/lib/cgi-bin">
AllowOverride None
Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
Order allow,deny
Allow from all
</Directory>
</VirtualHost>
NameVirtualHost *:443
<VirtualHost *:443>
SSLEngine On
ServerName private.proctinator.com
ProxyRequests off
ProxyPreserveHost On
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
ProxyPass / ajp://localhost:8009/
ProxyPassReverse / ajp://localhost:8009/
<Location />
Order allow,deny
Allow from all
</Location>
</VirtualHost>
Você terá que mexer um pouco nas configurações, mas isso deve fornecer a configuração que você descreve.