For those of us on JB 4.3
- Download the zip file from this post (credits @geoworld_200)
- Extract the 3 apks but copy only GoogleHome.apk to external storage
- Install (requiring temporary disabling of the "unknown source" security block)
- Run the app and it will invite use of GoogleNow which you can either accept or decline
- Press the physical "Home" button and you can now chose to use the Google Launcher instead of Touchwiz
I've tried this on my (rooted and custom ROM) P605 and it works just fine with no FC or issues so far. But, per usual, YMMV. And it obviously won't get updates via Play.
Presumably the same could be achieved for KK using the more recent version of the apk found here. But I haven't tested it yet pending a 4.4 ROM release ...