I have a Verizon Galaxy S3 with Jelly Bean on it.
What I want is to long-press the Home button and hear a beep to prompt me to provide a voice command.
I had it set up this way before I installed the official Verizon version of Jelly Bean. I had Cyanogenmod before.
I know that I can long-press the "Menu" soft-key to open up Google Now, but that's not what I want, especially since it doesn't even activate the voice search.