well.. follow up answer. I got most of this from other posts, but some of these steps are backtracking on my previous post. also, there's a giant "but" at the end of this one, just like the last one.
https://android.stackexchange.com/q...when-pushing-call-on-car-head-uni/36836#36836
Galaxy S3 Owners: Make Google Voice Actions (and now Google Now) the Default Instead of S-Voice | Standby.
1. uninstall "S For Switch Voice" if you installed it.
2. in S voice settings, uncheck the box to launch from a home button double-click (this may not be needed, but safety first)
3. in phone Settings, Apps, disable (turn off) both S Voice and Google Search (s voice can interfere with what we're doing)
4. install the app "Bluetooth launch"
5. in that app, scroll down to Google Search, expand it, and find com.google.android.googlequicksearchbox.voicesearchactivity. select it. the app should tell you it's "updated."
6. with the phone unlocked, tap your Bluetooth button. when prompted which app to use, choose Bluetooth Launch, always.
Bluetooth Launch will probably crash at this point since you have it configured to start google search, which is disabled. but we had to disable google search temporarily to trigger the prompt to choose bluetooth launch. so...
7. go back into apps and turn on google search (leave S Voice disabled, you don't need it)
8. with the phone unlocked, tap your Bluetooth button. you should get prompted again, choose Bluetooth launch again.
at this point the phone should launch actual google voice search /google now (via bluetooth launch) whether the phone is locked or not.
to get the double-click home button to launch google search/google now, install the "home2 Shortcut" app and configure the double-click to start 'voice search.'
sounds great, right? BUT.
when I reboot, the phone forgets that it's supposed to start Bluetooth launch when I press the Bluetooth button, and it goes back to the Google Search default, which launches our terrible voice dialer when the phone is locked. and the home button double-click to start Google Now doesn't work when the phone is locked like it did/does if S voice is enabled. so I may be going back to my original "S Voice plus S For Switch Voice" route, since my phone and its home button are usually within easy reach when I'm in my car without me having to avert my eyes from the road, so opening Google Now is just as easy as it would be if pressing the Bluetooth button on my steering wheel actually worked.
sucks that this phone can't remember the defaults I set for the Bluetooth button. what's funny/sad is that Bluetooth Launch still appears as a default in the phone's app settings.