Portsmouth have named Richie Barker as their new manager and Steve Coppell as director of football.
Wigan have announced Uwe Rosler as their new manager after agreeing compensation with Brentford.
The 34-year-old has agreed terms with Blues and passed a medical but the club are waiting on a visa application before a one-month deal is completed.
Former Senegal international Diop, who helped West Ham to promotion to the Barclays Premier League last season, has impressed on trial at St Andrew's.
He has also played in England for Fulham and Portsmouth, with whom he won the FA Cup in 2008.