Audio mute on Alpine CDA-7894

Hi, I recently installed an Alpine CDA-7894 in my vehicle.  This unit has a mute button that lowers the volume 10 decibles.  I find that the button is hard to find quickly (like when my cell phone is ringing) and that 10 decibles is not always enought.

The unit has an audio mute button (pink/black) wire that is intended to be wired to a cell phone for "auto-mute".  I can't use this feature because I use a portable cell phone rather than a car mounted unit.

Can anyone explain how this feature works.  I'm guessing that when the pink/black is sent to ground it will mute the radio.  Is this correct?  If so, I will mount a pushbutton switch in an area that is easy to locate so I can quickly (and hopefully completely) mute the radio when necessary.

Can I just install a switch to switch pink/black to ground?  I don't want to damage the radio but would like to have a quick full mute option.  Thanks for your help.

Thanks anyway.   I figured it out.  Sending the pink/blk to ground acts as an audio interrupt.  Just want I wanted.  Now I need to get the right sized switch.  Off to Radioshack