12 Dec, 14:42
Prop Cian Healy is expected to miss the start of the 2014 RBS 6 Nations after undergoing surgery on his injured ankle on Wednesday.
A familiar face for McCall at the club will be his former Ulster and Ireland team-mate Jeremy Davidson who has had a senior coaching role at Castres since last summer.
McCall stepped down as Ulster coach last month after the province's less-than-impressive start to the season.
As well as McCall's appointment, Castres have announced Alain Gaillard as the club's new sporting director. A statement from the club said: "These decisions were taken following rising dissent within the team and a bad start to the campaign."