Virtual host setup for Horde package?

Hi,

I've installed Horde+IMP on my system but I want to access it via
"mail.myhost.com" instead of "myhost.com/horde/imp/" so I put the
following in my Vhosts.conf:

<VirtualHost *:80>
ServerName mail.myhost.com
ServerAdmin http RemoveThis @myhost.com
DocumentRoot /var/www/html/horde/imp
</VirtualHost>

which does the initial redirect, but obviously files in the horde
package refer to each other using the URL "/horde/..." which doesn't
work. What's the best way to do this? Can I tell apache that any URLs
starting with /horde should be passed to the "myhost.com" host?

TIA, Barry.