I'm new to FreeBSD (only started tinkering about with it last week), and after lots of digging through the documentation, handbook, and many other online resources I managed to have my vnet enabled jail working in conjunction with ipfw in-kernel NAT. Both inbound and outbound traffic was...
cat <<EOF> /root/ipfw
ipfw -q -f flush
ipfw -q nat 1 config if em0 redirect_port tcp Public_IP_address:22 2222
ipfw -q add 10 nat 1 ip from any to any
ipfw -q add 00100 allow all from any to any via lo0
ipfw -q add 00200 allow icmp from any to any
ipfw -q add 00300...