Firewall/NAT

Hi

I want to configure m0n0wall po use a transparent proxy squid with the following configuration.

(http://maximebenoit.free.fr/config_squid1.gif)

rules iptables:

iptables -t nat -A PREROUTING -i eth0 -s ! 172.16.0.1 -p tcp --dport 80 -j DNAT --to 172.16.0.1:3128
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.6.0/24 -d 172.16.0.1 -j SNAT --to 172.16.0.4
iptables -A FORWARD -s 192.168.6.0/24 -d 172.16.0.1 -i eth0 -o eth1 -p tcp --dport 3128 -j ACCEPT

I just want to know how do this configuration with m0n0wall webgui, i was some problems with 'inbound' 'outbound' ... 

thanks