If i understand you correctly, you'll need to find the appropriate triggers in whatever map you're attempting to use the scriipts in.
There should be two triggers which are both set to 'Activated by: "Alpha" ' You'll need to change one of them to something else.
SetRadiomsg will set the text that the radio shows for the appropriate trigger. So:
1 Setradiomsg "Hello" will set (the trigger with 'alpha' as its activation)'s message on the radio as 'hello', 2 setradiomsg "hi" sets Bravo trigger as 'hi' on the radion, and so on.
I'm not sure whether 1 setradiomsg "Null" will cause the radio to display no text, or the word 'null'.
1 setradiomsg "" will do this just as well i think.