personally i think it is totally useless and dumb. but I had to try it out.
so here's how to get it on your Droid Razr HD and Razr Maxx.
(you could've found this by simple googling, but here you go anyway )
NOTE: you have to be rooted to be able to access the build files.
1) download the apk here: com.facebook.home.apk
2) go to your build.prop file in /system using something like root explorer
3) edit your build.prop file and add this:
4) restart your phone and open facebook homeCode:ro.build.product = GT-I9300 ro.product.device = GT-I9300 ro.product.model = GT-I9300 ro.product.name = GT-I9300
5) realize how dumb it actually is and delete it, but be glad that you were able to use it for a couple minutes on your razr