I've been researching how to do this without success. I tried modifying the syslogd startup script, but it doesn't seem to work. Maybe someone else could take a crack at it?
#!/bin/sh
#
# $NetBSD: syslogd,v 1.12 2002/03/22 04:34:00 thorpej Exp $
# $FreeBSD: src/etc/rc.d/syslogd,v 1.9.2.1 2004/10/10 09:50:54 mtm Exp $
#
# PROVIDE: rsyslogd
# REQUIRE: mountcritremote cleanvar
# BEFORE: SERVERS
. /etc/rc.subr
name="rsyslogd"
rcvar=`set_rcvar`
#pidfile="/var/run/syslog.pid"
command="/usr/sbin/${name}"
required_files="/etc/rsyslog.conf"
#start_precmd="syslogd_precmd"
#extra_commands="reload"
#_sockfile="/var/run/syslogd.sockets"
#evalargs="rc_flags=\"\`set_socketlist\` \$rc_flags\""
#altlog_proglist="named"
#syslogd_precmd()
#{
# Transitional symlink for old binaries
#
# if [ ! -L /dev/log ]; then
# ln -sf /var/run/log /dev/log
# fi
# rm -f /var/run/log
# Create default list of syslog sockets to watch
#
# ( umask 022 ; > $_sockfile )
# If running named(8) or ntpd(8) chrooted, added appropriate
# syslog socket to list of sockets to watch.
#
# for _l in $altlog_proglist; do
# eval _ldir=\$${_l}_chrootdir
# if checkyesno `set_rcvar $_l` && [ -n "$_ldir" ]; then
# echo "${_ldir}/var/run/log" >> $_sockfile
# fi
# done
# If other sockets have been provided, change run_rc_command()'s
# internal copy of $syslogd_flags to force use of specific
# syslogd sockets.
#
# if [ -s $_sockfile ]; then
# echo "/var/run/log" >> $_sockfile
# eval $evalargs
# fi
# return 0
#}
#set_socketlist()
#{
# _socketargs=
# for _s in `cat $_sockfile | tr '\n' ' '` ; do
# _socketargs="-l $_s $_socketargs"
# done
# echo $_socketargs
#}
load_rc_config $name
run_rc_command "$1"
#!/bin/sh
#
# $NetBSD: syslogd,v 1.12 2002/03/22 04:34:00 thorpej Exp $
# $FreeBSD: src/etc/rc.d/syslogd,v 1.9.2.1 2004/10/10 09:50:54 mtm Exp $
#
# PROVIDE: rsyslogd
# REQUIRE: mountcritremote cleanvar
# BEFORE: SERVERS
. /etc/rc.subr
name="rsyslogd"
rcvar=`set_rcvar`
#pidfile="/var/run/syslog.pid"
command="/usr/sbin/${name}"
required_files="/etc/rsyslog.conf"
#start_precmd="syslogd_precmd"
#extra_commands="reload"
#_sockfile="/var/run/syslogd.sockets"
#evalargs="rc_flags=\"\`set_socketlist\` \$rc_flags\""
#altlog_proglist="named"
#syslogd_precmd()
#{
# Transitional symlink for old binaries
#
# if [ ! -L /dev/log ]; then
# ln -sf /var/run/log /dev/log
# fi
# rm -f /var/run/log
# Create default list of syslog sockets to watch
#
# ( umask 022 ; > $_sockfile )
# If running named(8) or ntpd(8) chrooted, added appropriate
# syslog socket to list of sockets to watch.
#
# for _l in $altlog_proglist; do
# eval _ldir=\$${_l}_chrootdir
# if checkyesno `set_rcvar $_l` && [ -n "$_ldir" ]; then
# echo "${_ldir}/var/run/log" >> $_sockfile
# fi
# done
# If other sockets have been provided, change run_rc_command()'s
# internal copy of $syslogd_flags to force use of specific
# syslogd sockets.
#
# if [ -s $_sockfile ]; then
# echo "/var/run/log" >> $_sockfile
# eval $evalargs
# fi
# return 0
#}
#set_socketlist()
#{
# _socketargs=
# for _s in `cat $_sockfile | tr '\n' ' '` ; do
# _socketargs="-l $_s $_socketargs"
# done
# echo $_socketargs
#}
load_rc_config $name
run_rc_command "$1"