Need 2 interfaces with different counters on a single chart

I would like to have these two interface counters on the same chart for easy comparison:

Node=Riverbed1, interface=lan-intf, couter=bytes received.

Node=Riverbed1, interface=wan-intf, counter=bytes tranmitted.

This way we can easily compare the wan optimization results of our Riverbed Steelhead devices.

I could not find where I can include different intf counter types to a single chart.  Any help or suggestions would be appreciated.  Thanks.