Bukkit

How to edit villagers

First, type
/nbt %v select
and select the villager.
Start trading with it, and then close

1 Edit profession

/nbt %v Profession = 1
see http://www.minecraftwiki.net/wiki/Villager#Professions
it affects the skin and offers (if he had not started to trade)

2 Edit offers

Villagers can only be edited via buffer or variable!
Create new compound and store to variable %t:
/nbt %t select compound
Create Recipes list:
/nbt %t Recipes = list

Create recipe

Create new compound and store to variable %r:
/nbt %r select compound
Create buy item as your item in slot 0:
/nbt %r buy = inv [0]
Or you can edit item manually:
/nbt %r buy.id = 1 short
/nbt %r buy.Cound = 1 byte
/nbt %r buy.Damage = 1 short
/nbt %r buy.tag.display.Name = "Item name"
(not recommended to change the display.Name of buy item)

Create sell item like above:
/nbt %r sell = inv [1]

You can create buyB item:
/nbt %r buyB = inv [2]

Append recipe to list

/nbt %t Recipes[] = %r
If you want to create another recipe, go to "Create recipe"

Append recipes to villager

/nbt %v Offers = %t

Done!