Stack alterations for complex jazz chords

Take a look at this jazz chart "Digital Gurney" I inputted into musescore: http://musescore.com/score/24879
It has a lot of complex jazz chords with multiple alterations, such as the first chord Bb▵#9#5. Musescore renders simple altered chords such as Bb7b9 very nicely by making the b9 as a superscript. However, when there are multiple alterations, it simply writes them out consecutively horizontally. I would like these alterations to be stacked vertically on top of eachother with a smaller font. I am a programmer and am willing to implement to contribute to the code base.