IPCop on VMWare against a Cable Modem without IP Address

Recently I had to setup a virtual IPCop using a cable modem that didn't have an IP Address.
The "normal" way of bridging the physical NIC to IPCop's Red and Green interface didn't work.

My setup is shown in the following scheme:

The physical eth0 is being bridged over vmnet1 to the virtual eth0 (green) of IPCop

The physical eth1 is defined with the provider's specifications (public IP, Gateway etc.) This eth1 is NAT'ed over vmnet2 to  IPCop's Red interface. The Red interface is set to DHCP.