Props to this site for the helpful info.

1. Configure your first static IP Address and Gateway information as normal inside of /etc/network/interfaces. If you have multiple static IP’s in the same subnet using the same gateway you should be fine to add them as sub-interfaces with no problems.

auto eth0
iface eth0 inet static
        address 1.1.1.1
        netmask 255.255.255.0
        network 1.1.1.0
        broadcast 1.1.1.255
        dns-nameservers 2.2.2.2 3.3.3.3
        dns-search yourdomain.com
 Continue reading "Linux – Policy-Based Routing Enables the Use of Multiple IP Default Gateways"