Multiple external interfaces to be used by different groups

Dear sirs,
I am a newbie to Firebox and I am trying to configure an M400 that was already at our facilities.
The configuration I want to achieve is to configure eth0 and eth1 as external interfaces for accessing internet via two ADSL services.
Group A on eth2, set as trusted, needs to connect to internet via the service of eth0.
Group B on eth3, also set as trusted, needs to connect to internet via the service of eth1.

I have not found a way yet to setup a default route for each group to use the appropriate interface for internet access.

Can you please guide me on how this can be achieved?
Thank you!

Comments