http://developer.android.com/guide/topics/text/creating-input-method.html#GeneralDesign reads:
Because multiple IMEs may be installed on the device, provide a wa
If you have rooted device, you can use /system/bin/ime utility.
List all installed input methods: # ime list -a
Set google's keyboard as default:
ime set com.google.android.inputmethod.latin/com.android.inputmethod.latin.LatinIME