You can get to Memleben easily by public transport. Continue from Naumburg Hauptbahnhof (central station, ICE-stop) with Burgenlandbahn (regional train) to Nebra where you can take the bus (Kupfer-Wein-Line) to Memleben. The bus stop is right in front of the monastery. One hour travel time from Naumburg Hauptbahnhof.
To plan your individual travelling route, click: http://www.starker-nahverkehr.de/