Normally, MMS uses the MuseScore graphics to display musical notation. However, for specific graphics like some children method books, we have developed a method to replace the MuseScore graphics with another svg file. The coordinates of the notes are then marked manually. Examples are found in the collection 395 (Alfred's Premier Piano Course Lesson 1A).
To create such an exercise:
1) Create a normal exercise with exactly the same line breaks as in the graphics which you plan to use as the replacement
2) Convert the new graphics to svg (you'll need a good quality source file). In Linux, use the pdf_to_svg.sh script that Margus wrote.
3) Use the MMS svg cropper to cut the new svg into slices
4) Open the exercise and replace the word 'exercise' with 'replace_images' in the URL
5) Load replacements line by line and map the noteheads by clicking on the svg file. Note! You'll have to make the first click somewhere far left on the score.