The 19-year-old took his tally for the Dons to four in five games with both goals in the 2-2 draw with Wycombe on Saturday.
McCallum is due back at parent club West Ham next week but accepts his first-team opportunities are likely to be limited at Upton Park this season.
"If I am not in the plans at West Ham now, and I do not think I am because they have just signed two strikers, then I would gladly stay here longer if the gaffer wants me," he told the Dons' website.
Manager Neal Ardley is eager to keep the in-form frontman at Kingsmeadow.
He said: "That is the best Paul has played for us.
"Apart from the goals, his work-rate and the way he used his body was good. We have worked on him and he is growing as a player - it is great for him to get another two goals."