Workers on the Spam line in Austin ??? more than 40 of them work two shifts ???see no signs that their work schedule will let up.???We are scheduled to work every day except Thanksgiving and Christmas,??? said Darwin Sellers, 56, a Spam ???formulator??? who adds salt, sugar and nitrates to batches of Spam. ???Mr. Ettinger is negotiating with the man upstairs to get us to work eight days a week.???