Can you provide me a sample about how to integrate LLBLGenPro generated code with Enterprise Library validation application block?

Here is a discussion about that: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=11384

Now in v3 you can specify extra attributes to entities/fields. Also in 3.5, you can create buddy classes to decorate entities. I never used that application block but looking at the above thread I think that would be definitely possible.