Step 1: "Radio Configuration > Display & Menu > Radio Lock / Tactical Inhibit" tab

Step 2: "Radio Configuration > Display & Menu > Menu Items" tab - add "STUN" and "KILL" menu items

Step 3: "Conventional > ASTRO Systems > ASTRO System > ASTRO System - # > Data" tab

Step 4: "Conventional > Conventional Personality > Conventional Personality - # > Rx Options" tab - must be set to "ASTRO"

Step 5: "Conventional > Conventional Personality > Conventional Personality - # > ASTRO Call" tab

If you've already got TMS working then you should really only need steps 1, 2 & 5

I note with step 3 that the help screen says "Auto Generate IP Address" and "Auto Generate Target IP Address" must be checked, however that will be a problem with mobile radios as I'm pretty sure they don't have that option? But from what I can see, Tactical Inhibit just works over P25 data so as long as that's set up and working it should send inhibit commands?