I almost did this, but not for journalism. I was part of a (legal) weed grow, but my coop and I were just interested in some of the finite points of policing, and what better way to learn?

I never got past the inception, though.

What I did pull the trigger on was TSA screening. I didn't take the job, but I did get through all the selection stuff. They actually train you a bit on x-ray scanning and what I learned was really useful.

They aren't looking for drugs at all, ever. If you're flying domestic, go ahead and take some weed to your mom. I always do. I even check it in my checked bag. Just never pack more than an ounce, and only if you can afford to lose it. In legal states, the worst that will happen is they throw it away. They don't have time to hunt you down to cite you.