This is for the Verizon LTE version of the Samsung Galaxy Nexus.
I am tasked with writing a tiny app that will effectively disable/enable 4G capability. This can be done
http://developer.android.com/reference/android/provider/Settings.System.html
Aside from writing the code in your Activity.java, you will probably have to ask for permission to access these settings in the AndroidManifest.xml. So it's annoying but should be simple enough.