Hmm... I cant think of an easy way to do that. The normal behavior for any ammo outfit is that it works until the moment you launch it, then its effects dissapear. I cant think of how to do this other than a mission.
You could use a dude with a linkmission, but thats kinda clunky, especially if you want it to work everywhere.
Actually, for some uses it is kind of elegant.
"You open the comm channel with the other captain as you order one of your men to launch the scrambler. You demand to know why a member of the Federation navy would fire on a clearly marked and registered passenger transport which, you add, is currently transporting a VIP. The other captain stands strong, but someone indicates something from just out of view. Suddenly, he wilts.
"I appologise for any inconvenience, sir. A full report will be filed. Please, continue on your journey. If you need help, we'll be glad to offer free repairs."
You close the comm channel, smiling.
(starts a mission that makes a special ship looking like the jammer jump into the system. Adds the IFF jammer outfit to player)