The Spireites appointed Lee Richardson as caretaker boss and he has moved rapidely to bring in Knill as coach until the end of the season.
Lee Richardson said: "Avoiding relegation will be down to a team effort so I am delighted that Alan, who is a young bright coach, is joining our backroom team to support me during a crucial time."
He added: "Since our playing days at Halifax Town I have been in regular contact with Alan. As he is currently out of work I have invited him along to help our immediate cause and I am pleased he is very willing to come."