Looking for a diagram showing how to hook up a direct TV receiver but keep an existing antenna for local stations.

Please be a little clearer here : what is it you want your TV to do?
What do you mean with "a direct TV receiver" ?
Do you perhaps mean that you want cable and an outside antenna simultaneously?

If so : is your cable going directly into your antenna connection of your TV, or do you use a converter box with a cable from there to your TV?

You could use a low-loss splitter connected to your television to combine both signals...

Just first answer these questions !

:)

From dish to receiver, from receiver to TV. There is also a spot for antenna input on receiver.
Or, If TV has multiple video inputs, use the "F" coax fitting for antenna.

Please be aware that unless your TV is a HD TV, you will not be able to receive off air broadcasts after February of 09.

At that point, all off air broadcasting will be in High Definition format.