I would like to make a mortar field with smoke.

I have read this article about an explosion mortar field.
http://developer.valvesoftware.com/wiki/Mortar_Field

And I have change it to a push_button, so it is called once,
when you push the button.
I just set the Target Input of the env_explosion to Explode.
It is simple and works just fine.

Now I would like to change the explosion to smoke.
But I cant seem to figured it out.

First I tried with env_smoketrail, which look most like the smoke grenade,
but there doesnt seem to be a Target Input that tricker it on.
http://developer.valvesoftware.com/wiki/Env_smoketrail

Then I tried with env_smokestack, it has both Toggle, TurnOn and TurnOff.
http://developer.valvesoftware.com/wiki/Env_smokestack
It works but only once.
The env_smokestack dosnt have a "repeatable" flag like the env_explosion.

So...

1) Is it possible to turn on and off the env_smoketrail?
2) If not. How do I turn on and off the env_smokestack repeatable?
3) Or can you quide me on to some other solution?

Hmm the smokestack should be repeatable, the toggle input would be kinda senseless if not.
Anyway, you could try to use the rate input instead (0 = off, somehow).

You could do it the hard HARD way and make it spawn an env_smokestack or env_smoketrail every time, then turn it off. I'm not quite sure how you want it set up or the series of events goes.