Should look something like this.
Code:
<VirtualHost X.X.X.X:80>
ServerAdmin [email protected]
DocumentRoot /usr/home/blah.com
ServerAlias blah.com *.blah.com
ServerName www.blah.com
ScriptAlias /cgi-bin/ /usr/home/blah.com/cgi-bin/
ErrorDocument 401 /401.html
ErrorDocument 402 /401.html
ErrorDocument 403 /401.html
ErrorDocument 404 /401.html
</VirtualHost>