On Galaxy S3 with Jelly Bean, how can I make long-pressing the home button activate Google Voice Search? 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.
You could install an alternate launcher like Nova and assign the buttons to do different things. Alternatively you can flash a ROM that has the home button going to Google Search by default.