Rhythm notation for jazz arrangements

Yes, it's possible, and in fact I specifically designed the new slash facility to make this easy. You don't say if you're trying to use the old slash plugin (which won't work, so you can give up now) or if you have found the new slash facility under Edit / Tools. With the latter, there are two new commands: Fill With Slashes, and Toggle Rhythmic Slash Notation. You'll want to use them both as follows:

1) enter the "accents" in voice 3 - for drums, easiest way is probably to enter in snare durm then use Edit / Tools / Voices / Exchange Voice 1-3

2) Select the range containing the notes you want converted

3) Edit / Tools / Toggle Rhythmic Slash Notation - this converts any selected notes to slash notation - on the staff for voice 1, hovering above for voice 3

4) with that range still selected, Edit / Tools / Fill With Slashes

If you need the accents to be represented without slashes as depicted, then after step 3, right click a note, Select / All Similar Slements in Range Selection, and use the Inspector to change the noteheads. That would also be a time you could adjust the amount by which they "float" above the staff (you'll see they have their "Chord / Vertical offset" set to -0.50).

You'll need to adjust the height of the rests manually the same way (right click, select..., inspector). I may decide to do that automatically in the command, but right now it isn't clear if this is always the right thing to do. Also I am aware there is a bug with the beam placement with small slash-headed eighth notes.

I would like input on the defaults for how "accent" notation is created (rhythmic notation for notes in voice 3). Right now, it's small slash-headed notes floating above the staff. My impression is that this is most common and appropriate for lead sheets - "regular" noteheads would be too easily mistaken for actual notes to be played. But looking at the jazz big band and combo charts I have on hand, and checking a couple of arranging textbooks, I see that normal noteheads are actually more common, and they don't necessarily "float" - they look just the picture above.

I am considering changing the default just for drum staves - regular heads, no float.

In both cases, I may yet decide to move the rests up as well. One thing that stops me is that this part of the code would not necessarily know where multi-voice rests are placed by default - and who knows if we'll change that default (or make it a style option) some day.