The 31-year-old netted the equaliser from the penalty spot in stoppage time, cancelling out Massimo Luongo's 70th-minute effort.
The Bees manager told Sky Sports News: "Kevin is excellent. He had not played for a long time but stepped up to the plate. It was a difficult situation for him as he was not playing many matches, but in all the games he looks very solid and does a great job.
"Obviously, in the end, he used all his experience and skills to convert the penalty and I'm very happy for him.
"The tie is wide open and I said before the game, we must make sure it was. To get a draw after all the circumstances of last week was a very good result."
The second leg of the tie takes place at Griffin Park tomorrow.