fm-gate2# route add -net 192.168.3.0/24 192.168.0.222
add net 192.168.3.0/24: gateway 192.168.0.222
fm-gate2#


Add a line to /etc/hostname.{if} like this
! route add -net 192.168.0.0/16 192.168.2.1
or whatever. See man hostname.if