how to configure xbiff

[Pieter Donche]

FreeBSD 7/KDE 3.5,  /usr/local/bin/bash in /etc/passwd as login shell

I used to have xbiff (displays a mailbox icon with flag) on Solaris, 
which notified me whenever a new mail arrived in my mailbox 
/var/mail/USERNAME, via a beep and the flag in the mailbox icon
being raised.

What precise command do I have to write in what startup file, 
so that this does the same thing on FreeBSD/KDE3.5 ?