Marsella has joined the club on a part-time basis and will work with the three keepers three times a week and on match days.
The Iceman told the official site told the club's official web-site: "I have appointed Steve as he is someone I know well and have worked with before at Barnsley and Notts County. He will work here on a part-time basis for the time being to see how that works out.
"He will work with the goalkeepers three times a week and on a matchday.
"It is something that will benefit the goalkeepers, because I've said before that sometimes the goalkeepers feel a bit neglected in the training sessions. They feel they can be left in the corner and I'm sure they will enjoy working with him."