
Keen, who watch Colchester's defeat to Rochdale from the stands, will be joined by David Wright, who will be Keen's assistant.
The 48-year-old began his coaching career at Macclesfield, before he joined West Ham.
He joined Liverpool as first-team coach in 2011, before spending time at West Brom, Fulham and Reading.
U's have been without a manager, since the departure of Tony Humes last season.