Thanks to the guys at FreeBSDDiary.org for pointing in me the right direction (their instructions are for clients).

• cd /usr/ports/net/isc-dhcpd2
• make
• make install
• Be aware that install creates the file /etc/dhclient.conf; I did not change mine.
• It did not make/install an automatic startup script, that's left up to you. See my webpage HowTo Autostart for help on this.
• Make sure your kernel has pseudo-device bpfilter 4. See my webpage HowTo Build a Kernel for help with this. (If you made a new kernel, you'll now have to reboot.) (Note that in 4.2 this appears to have changed to simply 'pseudo-device bpf' and seems to be on by default.)
• Make sure you have the appropriate /dev/bpf* entries. Use 'sh MAKEDEV bpf0 bpf1 bpf2 bpf3' etc. to create them if not present. (Note that in 4.2 this seems to have been done by default.)
• You'll need to create/edit a new /usr/local/etc/dhcpd.conf. Mine is included in it's entirety below.
• For detailed help once installed, simply use 'apropos dhcp' to quickly find all the related manpages.

Sample listing: (/usr/local/etc/dhcpd.conf)

#
# dhcpd.conf for vintners.net (brix)
# MikeL  06-Dec-2000
#

option domain-name "vintners.net";

# Reminder: the following names are the INTERNAL network names...
option domain-name-servers balling.vintners.net, oechsle.vintners.net;

# I don't know if netbios is needed, but this is how it would go...
# Again, remember to use the INTERNAL network name(s).
# option netbios-name-servers epernay.vintenrs.net;

# Reminder: the following names are the INTERNAL network names...
option routers balling.vintners.net, oechsle.vintners.net;

deny bootp;

subnet 192.168.0.0 netmask 255.255.255.0 {
    range 192.168.0.20 192.168.0.250;
}

subnet 209.162.136.0 netmask 255.255.255.0 {
}