Visit Your Police Station
It is fairly simple to set up: just call your local police station. We called the department in the area we wanted to meet with, told them we had a gaggle of kids who wanted to meet policemen up close and see the cars, and they arranged a special time for us to come by.
Once we arrived, we were taken into the conference room where 2 very friendly offices in uniform walked the kids through a safety guide/coloring book. It was perfect in length and tone: short and sweet and kid-centric. They covered topics such as "how to identify a police officer," "what is 9-1-1," "wearing your seatbelt," and "not talking to strangers." Parents: you are also free to ask questions during this time.
After the little presentation, the officers took all the kids outside where they could sit in the police car, with the lights running. At one point they even got to hear the sirens on.
Again, even though we visited the police station in one district, the process and the event vary very little wherever you are. In fact, the police officer I was asking questions of said that there isn't even a minimum requirement for age or the number of children to set one of these up. If they have the time and you set up an appointment, they love to do this. The literature at each police station is the same, too, for the kids.
Our group loved this event. I would say that ages 3 and up are probably going to get the most out of this, but my son is just under 3 and keeps talking about this excursion. So it obviously had an effect.
By the way, you can also talk to the police about fingerprinting your child while there. Our playgroup has had a lot of discussions about doing this for identification and safety reasons. We did not do any fingerprinting while on this visit but do feel free to ask the police if they could accommodate such activity when you go. Alternatively, there are many at-home kits out there for you to take advantage of that are very cheap (see something such as http://www.protectyourchild.com/).
To start your planning, find where you want to go here: http://www.usacops.com/nc/. Then pick up the phone, call them, and start the process.
Visit to your local police station
Find your spot at http://www.usacops.com/nc/ and call!