wannabe - we just see our role as parents differently to what we did before we read about this way of parenting. We genuinely find that, (although it took a long time of doing it to get the 'we are in charge-you must do as we say or we'll punish you' attitude out of us and the children), all we ever need to do is sit down with them lovingly (ie. physically showing them we love them) and speak firmly about why doing whatever it is is unacceptable.
But most important, we find, is making it clear that we take them as seriously as we take eachother so, just like I wouldn't tell my husband to stop being stroppy or I'd stop him going out later, I don't do the same to my children.
With my husband, I'd say how it was making me feel, try to find out why he was stroppy, ask him what he thinks we could do to stop the stroppiness etc.
I know so many parents whose children still hit eachother (for instance) despite years of punishment for such behaviour, so it clearly doesn't work; and Kohn (and other writers - I certainly would never subscribe completely to what one person says - just take the bits that make sense to me...) would say that it can make the situation even worse. If your child doesn't misbehave because he's frightened of the consequences, then you've not actually taught them what you want them to learn - that hitting isn't a helpful, or moral, way of dealing with things.
If you sit down with your child(ren) and talk about why it isn't helpful to hit, and show them that they've both got upset and angry and not got any closer to sorting out whatever the problem was, then they learn that it's not only unkind and unacceptable to do that, but that it's counterproductive and doesn't make either member of the exchange happy. The thing to do, IMO, is to teach them better ways to do things, which they soon realise actually are more helpful and more enjoyable and more efficient etc.
It's hard work, though, when I'm losing my temper myself, and the first thing that enters my head is to yell at them and tell them to go to their rooms but taking a step back and apologising for speaking in the heat of temper and suggest we sit down and talk about it more calmly is usually way more effective.
This is a good website to read if you're interested