Using Postgres aggregate functions with NHibernate

[cs]

I have the following query:

SELECT title_id, title, array_agg(g.name)
FROM title t
INNER JOIN title_genre tg USING(title_id)
INNER JOIN genre g USING (genre_id)
GROUP BY title_id, title
ORDER BY title_id
LIMIT 10
Sample output from this query:

5527;"The Burbs";"{Suspense,"Dark Humor & Black Comedies",Comedy,"Cult
Comedies"}"
5528;"20,000 Leagues Under the Sea";"{"Family Adventures","Children &
Family","Ages 5-7","Book Characters","Family Animation"}"
5529;"2001: A Space Odyssey";"{"Classic Sci-Fi & Fantasy","Sci-Fi
Thrillers",Classics}"
5530;"2010: The Year We Make Contact";"{"Sci-Fi Dramas","Alien Sci-
Fi","Sci-Fi & Fantasy","Dramas Based on Contemporary
Literature","Psychological Thrillers","Dramas Based on the Book"}"
5531;"The 39 Steps";"{"Dramas Based on the Book","United
Kingdom",Thrillers,"Espionage Thrillers","Dramas Based on Classic
Literature",Suspense}"
5532;"4D Man";"{"Classic Sci-Fi & Fantasy","Sci-Fi & Fantasy","Sci-Fi
Horror"}"
5533;"8 Seconds";"{Drama,"Romantic Dramas",Biographies,"Indie
Dramas","Sports Dramas","Miscellaneous Sports","Sports Stories","Other
Sports"}"
5534;"9 1/2 Weeks";"{"Steamy Romance",Romance,"Romantic Dramas"}"
5535;"About Last Night...";"{"Romantic Dramas","Romantic
Comedies",Romance}"
5536;"Above the Law";"{"Action & Adventure","Action
Thrillers","Martial Arts"}"
(1) How do I create a NHibernate criteria around the array_agg
function? Will I need to extend the PostgreSQL dialect in any way to
accommodate this?

(2) I'm using SQLite as my integration test database and PostgreSQL as
my test/prod database. SQLite does not have the array_agg function,
but does have a group_concat function that does something similar. Is
it possible to set something up where I'll be able to use SQLite in my
tests and PostgreSQL in test/prod?

(3) array_agg returns data as an array. I found a great article on
nhforge (http://nhforge.org/wikis/howtonh/use-postgresql-arrays-with-
nhibernate.aspx) that explains how to extend NHibernate to handle
PostgreSQL arrays. How do I include this in my criteria? For example,
let's say I want to find a title that is in the Drama genre that is
not a romantic drama.

Thanks in advance for any help!