My chickens seem to enjoy getting a bath. A few do not, but most do.
I use either a laundry tub, or one of those rubber gardening tubs. I put it in the bathtub under the faucet, put warm water in it almost to the top. Like what RikkiMarie said above, put a towel down for traction and don't have too much water in the tub that the chicken starts to float. The water usually comes to about their 'shoulder' height. I use baby shampoo , but sometimes I use just plain water, or salt -if I'm doing it to get rid of mites. Try not to let your chicken drink the water! I also bought an herbal natural shampoo of lavender and thyme, but this doesn't lather up so much. I thought it would be good to stave off bugs. I have no conclusions about that yet. ..... Oh I should note that I never wash their head. I don't wash chickens 'professionally' for shows or anything like that, I just usually do it to get poopy bottoms clean, or if the chicken needs a bath for some reason.
Once I'm done lathering them up, getting in between the feathers gently, I pick them up and tilt them side to side and rinse then under the spigot- warm water of course. (never use cold, or too hot- you can shock their system.) I put a towel around them when they are done to get most of the water off of them, then blow dry on warm heat with the hair dyer. <Note: Some hair dryers can suck feathers into the vent- so do be careful. I always hold the hair dryer a few feet away from them.> They don't always like the hair dryer, but I think after a while, as long as you are careful about not heating them up too much with it (always keep it moving) they seem to like it.
I have one of those old hood hair dryers and I'm thinking about giving a try with the chickens if I can make sure it is safe to use with them. I think they would absolutely love the massaging streams of warm air. I can just imagine a hen sitting under that thing, sleeping while drying off.
I think if you have more 'wild' chickens it would be more difficult to bathe them. My chickens seem to trust me a lot and I can walk right up to them and pick them up, so of course that can make a difference. I do think that once a chicken gets used to the warm bath, it will like it and calm down.
I have to say that the show wash kits sound interesting. I will have to look into it!