okay, there are a few ways that things like that can be documented... most of which are not easy. the way that I've found that works good, is go out there with a tape recorder, keep yourself calm, try not to show any fear of where you're at. Sit down and turn the tape recorder on. (make sure you have a very long running tape) and just start to have a conversation, once you're all a little comfortable with where your at and the likes, start trying to talk to 'them'. Once you've been in an area for a while and the energies settle down, if 'they' are out there, they settle and be curious (provided there wasn't a tragic death where the spirits are angry) and you may not hear them, but just say things like 'if you're out there, don't fear us, we don't mean to upset your balance' or something like 'we'd like to help answer your questions' just TALK to them... candles are good too, as flashlights illuminate dust particles and candles offer a warm soft glow. try to find out the history of the place, and relay that into your conversations. just let the recorder go until the tape runs out. then when you get home, play it back, but you have to turn the volume up VERY loud, because if you can catch them on the machine, they are extremely hard to hear... that's why people use techniques that they can transfer into a computer and isolate the different sound waves.
Now if you really want to dabble in this stuff... take a ouija board out there... but that can get really strange and sometimes you find things you don't want to find... so best to stick with trying to lul them into talking to you.
Most spirits that stay on this plane, are looking for someone who can help them, and once in a while, they'll find a subtle way of letting you know they're there.... but just talk to them, it can help keep them calm and respectful. Sometimes it can help the group of people to gather in a circle and create a 'protection circle' around you, just stand holding hands and picture a blue ciricle around your group that will keep harm out.... that way, you'll only get the friendlier spirits.
hope this helps... I don't recomend dabbling in this stuff, especially if anyone in the group is 'sensitive' to any form of spiritial energies... but if you're determined, try those methods!
Walkie talkies and cell phones will sometimes pick up things, you wont really be able to understand them, but you may be able to hear things.... but you can't really record that...
Personal experiences in my life and information from others.