Johnson, who bagged 29 goals last season under Paul Hart, has been out of action since suffering a broken leg against Sheffield United in September 2003.
He told the official website: "I'm hoping to play 45 minutes of Wednesday's game and I'm really looking forward to it.
"I've been out for a long time now but I've had a couple of weeks of hard training and I feel ready to make the next step – playing games."
The game is a 7pm kick-off and is taking place at The City Ground.