1: First of all, you will need the face unlock apk file. This can be found at system/app/com.android.facelock.apk. To get it off of your phone, enter the following command sans quote marks: "adb pull /system/app/com.android.facelock.apk com.android.facelock.apk". You will find the file in the folder which has adb has been setup in.

2: Now you need to decompile the apk file via apk tool. Place the apk you pulled from your phone in the apktool folder for simplicity's sake, and run the following command: "apktool d com.android.facelock.apk faceunlock". Now wait for the process to complete.

3: In the apktool folder, you will now find a folder called faceunlock. In here is where the magic will happen. You will see a folder within this named res and in here a bunch of folders called values-x (Where x is two letter language codes). Open the folder relating to your language code and open the strings.xml file with a text editor.

4: In this file you will find a list of different text strings. Edit these as you prefer, it's quite self-explanatory what does what. Try to keep the text length about the same size as the original, I'm not sure what will happen if it gets too long. When you're done, save.

5: Now we need to recompile the changes! To do this, execute the following: "apktool b faceunlock newunlock.apk". Wait for this process to complete.

6: If you were to just rename and copy this new file back to your phone, it wouldn't work, due to it not being signed. To get around this, we cheat! rename newunlock.apk from your apktool folder to newunlock.zip. Then rename com.android.facelock.apk to com.android.facelock.zip. Open both files in a zip editor, such as 7zip and delete the resources.arsc from the original, unedited file (com.android.facelock) and transfer the same file from the modified file (newunlock). Close them both and rename com.android.facelock.zip to com.android.facelock.apk.

7: Finally, use adb to push the com.android.facelock.apk file which you have now added the edited resources file to your phone. Do this
with the following command: "adb push com.android.facelock.apk /system/app/com.android.facelock.apk".