Create Tuplet Tremolo
I am trying to transcribe a score and I encountered a problem. I have to make a chord tremolo with a sextuplet. I posted an image of what it should look like. The song is in 6/4 time, and it looks like the tremolo repeats the notes three times, similar to the triplet rhythm directly before in the image. The style of the tremolo is the same as an eighth note tremolo, but with a 6 on top, indicating it's a sextuplet.
Firstly, how would I go about doing this? I have no idea.
Also, as a bonus, does anyone know how to make the tremolo line touch both stems of the notes like eighth note beams?
EDIT: Updated photo to a better example.