The Liverpool star has a broken toe but McClaren desperately wants him in his team for Saturday's crucial Euro 2008 qualifier at Wembley.
And he is ready to face a backlash from Rafa Benitez after the Anfield chief made it clear he does not want his midfielder to have an injection.
McClaren said: "Steven played with an injection against Chelsea a few weeks ago.
"I have to do what I have to do to ensure we get the best players available for us and to help us win this game on Saturday."
England's medical staff are still hopeful Gerrard can get through the match without a jab.
"I've known it at club level where we've done that, where it's too painful to play without one. But there is no risk of further injury.
"We'd take whatever action is needed to get him on that field. But we will take Liverpool into consideration, speak to Rafa and the medical team."
Asked what would happen if Gerrard needed an injection and Benitez remained against it, McClaren replied: "We'll cross that bridge when we come to it.
"I'm very, very confident Stevie G will be with us for what is a very important game.
"He wants to play, I want him to play, the team does, the fans do. The country does.
"It's a big game and we need big players. Stevie is one of them. Sometimes what the players want has to be taken into all the advice given from medical people and from managers.
"We will go a lot on Stevie G, on how he is feeling and what he wants.
"We will liaise with Liverpool and will do nothing that will put the player at risk."
Asked if he had the ultimate power to decide whether or not Gerrard plays, McClaren replied: "Yes, I think I have."