Born 10 January 1988 in Leeds, England, McIlorum was a Farnley Park High School pupil and Leeds amateur at Stanningley and Queens. He had been selected for England U16s in 2004 and joined Wigan's under-18s Academy in 2005.
McIlorum signed a two-year full-time contract with Wigan in July 2005, keeping him at the club until the end of 2007. McIlorum was selected for Yorkshire U17s after joining Wigan in August 2005. He was also included in the England U17s squad to take on the touring Australian Institute of Sport in 2005. He capped the 2005 season by winning the Wigan Supporters' Association Under 18s Player of the Season award.