The Royals face Dave Jones' side on Friday evening as a result of their fifth-placed finish in this season's Championship league table.
McDermott told the club's official website: "The players are ready, they are focused and Friday can't come quickly enough, to be honest. I'm sure Cardiff feel the same.
"As a group we've spoken about what's required, and one of the most important things is to enjoy it. We'll be ready.
"I've got such a good group, every single one of them is ready to play. We made changes at the weekend (against Derby) and every player showed once again that they can play in this team.
"We want to beat them, they want to beat us, we want to get to Wembley. Both games will have a great atmosphere - it's all to play for."
Source: PA
Source: PA