I'm wondering if it's possible to activate active camouflage by pressing the flashlight button.

on a biped or vehicle. I believe the covie tanks on downflow activated a cloak by hitting the flashlight button.

For a single player map, easily. Although it would be permanent, because you can't deactivate camouflage by scripts, as far as I know.

But, to make legitimate camouflage (not permanent), you could make a script that checks to see if your flashlight is on, and then creates, attaches, and detaches an active camouflage powerup to you in each tick, giving you camouflage. You just have to get rid of the camouflage sound and the tint, because it would constantly annoy you to death (I'm not sure how to do this, it's bound to be in the UI tags somewhere). You also need to edit the powerup to have a 1 second time, so that when the flashlight turns off, the camouflage doesn't stay activated.

Then, you could have camouflage for as long as the flashlight is on.

If you're talking about a multiplayer map, then this could still work, only you need one powerup for each player, you need to make sure only the host accesses the powerups, and you'd have to make the powerup invisible so that other players can't see it floating on you as you're camouflaged.

So, it's possible, just lengthy.

Yeah, I just needed a non-permanent one, else I would've used (cheat_active_camouflage).

Yes. That's exactly what I meant.