Answering my own question.
Yes, it can be done, now I'm using Endian with one NIC as web filter.
just use one NIC and configure the RED interface as Gateway and point it to the router IP at first step of network configuration.
then configure your workstations to go through Green interface IP.
Step 1/8: Choose type of RED interface
ETHERNET STATIC
ETHERNET DHCP
PPPoE
ADSL (USB, PCI)
ISDN
ANALOG/UMTS Modem