What you are looking for is something similar to TPH (http://msdn.microsoft.com/en-us/data/jj618292.aspx)
I don't think this will work for you however, as you have multiple existing tables.
One of the possible solutions is:
- Create a base class called "BaseModel" (or something like that)
- Add those properties as abstracts to force them to be overridden
- Create a method in that base class to populate those fields, or create a helper which takes BaseModel, IsDeleted,LastUpdated, LastUpdatedUser as a parameter and update the model.
- Extend the partial classes generated by the model.tt file and inherit from the BaseModel class.
Thanks, Dave