Ciao,
these are some tools that you can use to generate the mapping and classes for using NHibernate:
- http://altinoren.com/activewriter/
- http://sourceforge.net/projects/nhibernateaddin
this is the easiest, but has less options (you cannot use all the possibilities of mapping files) I use version 1.0.0.3, because the last has some bugs.
these two integrate in visual studio, and can map tables from visual studio server connections
I use the second because after instalation you simply add a new NHibernate Plugin object in wich you drag-and-drop the tables you need and creates you the mapping files and classes when you save the diagram.
- www.mygenerationsoftware.com
this uses templates that should be easy to modify, you have to find the most suitable
- objectmapper
http://www.puzzleframework.com/WikiEngine/WikiPageViewer.aspx?ID=90
this is a bit complex to use (beacuse there's not a manual :-) but it's interesting because you can start from model, classes or database and generate the others.
there's also this one
http://www.codeplex.com/Wiki/View.aspx?ProjectName=NHDomainMapper
but for this helps you only in writing mapping files, you must already have database and classes.
I suggest, if you want and have time, to try all of them and choose the one you prefer.