I need some advice on a headphones project from an electronics person

[dirtyJohn]

I have a Detectorpro Headhunter Landpro which is pretty much the same as the Wader with the addition of a probe. Both the coil and probe have screw on connectors. I'm interested in adding a 1/4 inch headphone jack and volume control so I can use this as a regular pair of headphones that I can use with my other detectors in addition to using it as a pinpointer (while still be able to use it as a metal detector when I want to). Basically I want to make this into a Detectorpro uniprobe. It seems it's already 90% there but I need some advice on where to start. I was thinking that a volume control connected between the speaker and 1/4 female headphone jack that clicks to the off position when switching to the probe so the audio from the detector doesn't interfere with the audio from the probe. This would be done to the battery side of the headphones not the side that already has the control knobs on it. I'm not an electrician rather a hobbist with all the soldering and other equipment to do this so please tell me if I'm missing anything? Any help would be appreciated.
HH
John