You can specify one single app unter Windows Phone 8 to show detailed informations on the lock screen.
In order to allow ICE Message to show it’s content on the lock screen you’ve got select ICE Message as the app that is allowed to show ist notifications under the lock screen:
On the main page tap on LOCK SCR SETTINGS:
This brings you to the WP8 Lock Screen Settings page. There you can select ICE Message from the list of lock screen notification apps:
and the result will look like that when someone else has in case of… (heaven forbids!)
will look at your lock Screen: