Hi Klaus, thanks for your reply! Yes, that function is great, that's the kind of thing I am looking for! This is already so much better than working on it manually. I have tweaked it a bit to my liking, particularly by setting \tweak Stem.thickness #6 for the stem that represents the cluster. I will try to see if I can come up with a way to automatically handle the stem up/down, as it would be so much easier if this function automatically detected those. Ideally, I think applying it to a chord (something like \cowellCluster <c' a'>4) would be the ideal solution. It also does not handle whole notes, as those do not have stems to be hacked. If I come up with something interesting I will make sure to post it here.
Many thanks once again! Gilberto
