I'm not sure if you want to wire this from scratch yourself. If you do it is easy to do with a standard dual gang 50k logarithmic potentiometer. Available from Farnell, Radio Shack, etc. The potentiometer needs to be logarithmic to give you the perception of a linear increase in volume.

You would connect the output of the equalizer to the top of the potentiometer and ground to the bottom of the potentiometer. The wiper of the potentiometer will then connect to the amplifier. This will then allow you to adjust the volume to the amp from straight through to infinite attenuation. If you didn't want to attenuate down to zero you could put some resistance in the ground leg of the pot.

If you're keen to wire this yourself I'll draw up a circuit, it's a bit hard to put into works but a very simple circuit.

Rod.