After a bit of searching, I found that Bose sells a mobile adapter kit for their Quiet Comfort headphones which includes a microphone and a single control switch for answering calls or switching iPod tracks but no volume control. I found a few other adapters that add the same functionality but again, no volume controls. Time for a bit of cutting, splicing, soldering and heat-shrink tubing.
I'll show you how to add a microphone, control switch and volume control to your Bose or any other headphone by lopping off the earbuds of your latest generation Apple earphones with remote and splicing the left and right earbud wires to your Bose headphone cable.
I've purchased at least 7 sets of the Apple earphones with remote only to always have the left earbud fail at some point. I've taken to purchasing them from Best Buy, requesting the Apple Store price, and paying the $5 for the replacement warranty. Needless to say, I have a couple of sets around with defective left earbuds.
Step 1: Start Your Splices
Strip about an inch of the outer insulation off each end of the cable. I used an X-Acto knife to score completely around the outer insulation. Pull off the insulation. One of the cables will have a copper/red pair and the other a copper/green pair of wires.
In addition, one of the cables (I think it's the left) will have a twisted red/green/white set of wires. Cut these off where they emerge from the outer insulation. I'm not sure what they are for, but I checked, and they do not connect to anything in the earbud itself.
Cut the cable coming out of your Bose headphones so that it is about 8 inches long. If you mess up, you can purchase a replacement cable for about $15 from the Bose online store. Strip about an inch of outer insulation from the end of the cable. This will expose 3 wires, a red, green and a copper.
Twist all three copper wires (1 from left iPhone cable, 1 from right iPhone cable and 1 from Bose headphone cable) together and solder. trim the end so that its length is about .25".
Step 2: Splicing the Left/right Wires
Apply heat shrink tubing to the copper (GND) splice, red splice and green splice. Shrink the tubing with a heat gun.
Step 3: More Heat Shrink Tubing
Cut a short piece of heat shrink tubing that has a diameter which will slide over the Apple 3.5mm plug and remote control. Slide the tubing up the cable so that it covers the red/green (left/right splice) on the white side of the cable as shown in the photo.
Use a heat gun to shrink both pieces of tubing.
Cut another piece of heat shrink tubing long enough to cover the entire splice as shown in the photo and shrink.
Cut a few short pieces of tubing to keep the dual leads on the iPhone cable from separating, position as shown and shrink into place.
Plug the Bose end of the cable back into your Quiet Comfort headphones.
Step 4: Enjoy Your New Headphones!
Since the headphones are noise canceling, it may sound weird talking on the phone without hearing your own voice. I usually position the right headphone cup off my ear slightly while talking on the phone so that I can hear my own voice.