On 5.3, I have following in rc.conf:
syslogd_flags="-a 192.168.123.0/24 -b 192.168.123.254"
on the machine that has IP 192.168.123.254. It serves a cluster of 192.168.123.X with X = 1 to 7
/etc/syslog.conf on the 192.168.123.X PCs has:
*.* @192.168.123.254
and all syslog messages arrive on 192.168.123.254 and are stored there.