Slater has not coached in the NFL but has run seminars and clinics on line play designed to help young linemen.
Jim Colletto, the line coach in 2005, joined the staff at UCLA after a season in which the Raiders finished 28th in rushing and gave up 45 sacks.
The Raiders are in the market for a special teams coach, as Joe Avezzano's contract was not renewed.
Tom Walsh, who was at Shell's introductory news conference last week, has confirmed he was interviewing for offensive coordinator position. Walsh served as an offensive assistant with Shell from 1989 to 1994.
He said his role is "to be determined," but it appears he will be introduced as the team's new offensive coordinator in short order.