Leslie has twice worked as a DEL head coach for the Kölner Haie. In January 1999, the Carberry, Manitoba-native succeeded Finnish coach Timo Lahtinen. The Haie finished 5th overall in the DEL that year but were stopped by the Frankfurt Lions in the playoffs. Leslie remained with the organisation as an assistant coach when Lance Nethery was brought in as new head coach during the 1999 off-season. Leslie again assumed head coaching duties for the 2000-01 campaign after Nethery decided to step down from coaching and serve as director of player personnel. Leslie's second head coaching stint with the Haie only lasted till January 2001, though. He was replaced by Nethery after suffering eight straight losses at home.
Leslie last worked with EHC Basel in Switzerland, where he was axed 21 games into the season last November. Prior head coaching stints include Austria's VEU Feldkirch and the London Knights of the British Super League. He also worked as an assistant coach for Team Canada, EV Zug and SC Langnau Tigers of the Swiss Elite League.
In 1998, Leslie won the Swiss Championship with EV Zug, working as an assistant for former München Barons coach Sean Simpson.