Change Horde Webmail URL

[zamarax]

Hello, I have plesk 8.2 and windows server 2003, what I am looking to do is add to the listening url or Host Header that horde uses for webmail, I know where in the DNS option I can make the changes but that does nothing for Horde, right now Horde is setup to listen for address webmail.DOMAIN.COM, I would also like to configure it to listen for plesk-webmail.DOMAIN.COM

does anyone know if this is possible? and where I can make the changes?

Thanks in advance!