Configure Legacy Ubuntu System to use VLAN with Eth0

We are using Ubuntu 10.04 for an embedded industrial system. Various systems have been deployed on hundreds of networks with regular DHCP or Static IP address configuration. But, we now need to connect with a system that is VLAN with ID 50. So, we need the exiting eth0 interface modified to use VLAN. Attached is a summary of the existing configuration. The issue is shown on the second slide, where packets have VLAN tags but our interface is not configured to use VLAN. We will configure a test system, and I will need the instructions. Old Ubuntu packages can be downloaded from archive, if necessary.