NHibernate: help translating an hql query to use criteria api instead -

After

I have the following HQL query which I want to switch to the Criteria API

 <(ac.Id , 0 code> serials, a.Name as the name, ActiveStatus, dbo.GetActivityStartDate (a.Id) StartDate, dbo.GetActivityEndDate (a.Id) EndDate as as A.ActiveStatus as a. Id select, insert) as CategoryID, in the form of a left external join (as ac.Name, '') CategoryName as a .category to join in the form of AC  < / Pre> 
 Obviously selection Lie Neither the initial properties are trivial (estimation. Property); My question is..how do I map the remaining 4 properties? 
 
 I think a registered custom bid is in the form of a custom quote  dbo.GetActivityStartDate  and  dbo.GetActivityEndDate  - so that much earlier It is taken for care only 
 

So ... know that the change has changed. I need to register the "ISNULL" function with my custom bid; Once I did that, this format was a simple thing to use in Projections.SqlFunction to extract data in I needed.