What's the best way of using coalesce keyword in Subsonic 2.2 query?

I want to create the following query using Subsonic 2.2:

SELECT coalesce(col1, col2) AS result
FROM someTable

Something similar to this:

DAL.DB.Select(
    string.Format("COALESCE({0}, {2}) as result",
        DAL.SomeTable.Columns.col1,
        DAL.SomeTable.Columns.col2
    ))
.From<DAL.SomeTable>()
...