This for sure installed on AOKP. At least it installed, I'll have to wait until Wednesday when they do the test to confirm it works.
To install (this is old, the link at bottom has a flashable zip.):
1. Copy the "CellBroadcastReceiver.apk" into "/system/app"
2. Change the permissions to "rw- r-- r--"
It wont be a normal app, but it should appear under Settings --> More... --> Cell broadcasts
Edit: rmkilc is awesome and made a flashable zip! Install-CellBroadcastReceiver-1.0.zip