This is almost exactly the wrong place to post this, since the vast majority here use AOLserver, but here goes nothing!
1.3.27 (RedHat version, from rpm):
Possibly relevant bits of httpd.conf:
<IfModule mod_proxy.c>
ProxyRequests Off
</IfModule>
<VirtualHost *>
ServerAdmin youremail@somewhere
ServerName somewhere.acornhosting.net
ServerAlias otherdomain.acornhosting.net
# do not turn proxyrequests on!
# turning proxyrequests on can allow your server to be exploited as an open proxy
# needless to say, this is a baaaad thing
# and will get you into major hot water with your upstream provider
ProxyRequests Off
ProxyPass / http://1.2.3.4:8000/
ProxyPassReverse / http://1.2.3.4:8000/
NoCache *
</VirtualHost>
Hope that helps. If not, you might try an Apache-related mailing list or forum?