How to add 'included columns' in an index

[Joseph Lam]

I know this is how  to add a simple index:

mapping.Map(customer => customer.Column1).Index("IDX_COLUMN1");

But how do I achieve something like below?

In SQL Server:

CREATE NONCLUSTERED INDEX [IDX_FOO] ON [CUSTOMER]

{

        [COLUMN1] ASC

}

INCLUDE

( [COLUMN2] .... )