The following sample will insert JobNumber as identity starting at 100 incrementing 1 into the column list:

USE pubs

SELECT EmployeeNumber = emp_id,
FirstName = fname,
MiddleInitial = minit,
LastName = lname,
JobNumber = IDENTITY(smallint, 100, 1),
JobLevel = job_lvl,
PublicationID = pub_id,
HireDate = convert(char(10),hire_date,112)
INTO #Employee
FROM employee
ORDER BY LastName, FirstName
GO
SELECT * FROM #Employee
GO