swap rx and tx graphs?

Is there any way to swap the rx and tx variables for graphing purposes? We have a cisco router that The Dude discovered, but it is reporting its rx and tx traffic backwards. At least from the perspective that I want to see it.

Our LAN is plugged into eth0 and the WAN is eth4. When I download a file from the internet the traffic graph shows heavy tx on both interfaces. I understand the LAN interface reporting tx traffic if it’s looking from the router perspective sending packets to my pc it’s sending (tx). But the WAN interface is receiving (rx) from our DSL circuit and sending (tx) internally to eth1.

MRTG had a simple fix for reversing the values, can something similar be done with The Dude?

Thanks in advance!