Zimbra 7.2 reverse proxy to arbitrary internal website?

I have ZCS 7.2 opensource installed at webmail.domain.com and mailman on mailman.domain.com/mailman.

I wanted to setup a proxy so that when someone goes to webmail.domain.com/mailman, the proxy would instead pull up the contents of mailman.domain.com/mailman.

With apache and mod_proxy I could do something like
ProxyPass /mailman https://mailman.domain.com/mailman
ProxyPassReverse /mailman https://mailman.domain.com/mailman

With the amount of customization in zimbra, is it possible (and advisable) to do the same with zimbra's web server? So basically a reverse proxy that forwards to an arbitrary internal website.