Support for importing classes in mapping.

I have many reporting queries. Totals from these queries are fetched into my custom classes.
NHibernate requires these classes to be imported.
In xml I had something like this:
<import class="DomainModel.BalanceTotals, DomainModel" rename="BalanceTotals"/>
and in FNH it was as simple as this:
ImportType<BalanceTotals>();
With mapping by code there is no way to do that.
I need a way to import classes by code. Better alternative would be to remove import at all: in Java's Hibernate it is not necessary (and not possible). It seems to be possible to do in C# because it was possible in Java.