Limiting radio to one person

[Bellum 10]

I am trying to implement this nuke script into one of my MP missions.

http://www.armaholic.com/page.php?id=8294

It's activated by using radio 0-0-1. What I need to do is limit the script so that it can be activated by only one person. What happens is, you press 0-0-1, then click on the map where you want the nuke to impact. Currently anyone can use the radio command and click on the map anywhere. I want the script limited so that only one person can call in the nuke by radio and click on the map.