Saw this technique to create datetime values over at SQLTeam:
DECLARE @Year smallint
DECLARE @Month smallint
DECLARE @Day smallint
SET @Year = 2007
SET @Month = 5
SET @Day = 24
SELECT DATEADD(month, 12 * @Year - 22801 + @Month, @Day - 1)
(Due to Michael Valentine Jones and Peter Larsson).