United beat the Cumbrians, who were were promoted to League One as champions of League Two, in a penalty shootout after a goaless 90 minutes in the Ibizan town of San Anonio.
But despite seeing his side miss three spot-kicks, McDonald was focusing on the positives for his side.
He told the News And Star: "Scunthorpe can have the trophy, as long as we can have six points off them in the season.
"I thought the game was played at a fantastic tempo. We were probably the better team int he first-half and created the better chances, but we gave the ball away cheaply at the back in the second-half.
"We've only been together for two weeks, and I'm pleased with the way they have responded."
Carlisle boss targets revenge
