Striker Morison joined the club last week as part of the player-plus-cash deal that saw Luciano Becchio move to Norwich, but was sidelined against Cardiff due to a thigh injury, while defender Warnock was an unused substitute.
McCormack was withdrawn from Gordon Strachan's Scotland squad in midweek through illness, but is feeling better and could play a part, while manager Neil Warnock is hoping Rudy Austin returns fit and well from Jamaica's goalless World Cup qualifier in Mexico.
Fellow midfielder Paul Green and defender Tom Lees have both returned unscathed from international duty with the Republic of Ireland and England Under-21s respectively.
Habib Habibou, another deadline-day arrival, is hoping to play a bigger part after he made his debut last week when replacing El-Hadji Diouf against Cardiff.
Boss Warnock, who has no new injury or suspension problems, also has the option of recalling midfielders David Norris and Michael Tonge, plus defender Jason Pearce.
Leeds last week