Multiple subnets

[Brad Bendy]

Hello-
I am wondering how I would go about having multiple WAN subnets coming over 
one ethernet interface, basically bridge mode I guess, then have firewall 
rulesets based on the destination IP. Right now I use m0n0wall with one WAN 
subnet, but I need to expand to have multiple CIDR blocks from my provider. I 
know there has to be a way to do this, but not sure how. Any help/links would 
be great!

Thanks
Brad