Hi Ted,
yes you can do this. Simplest way for this example, is just to keep adding 32nd notes just before the measure line. Extra notes turn red for your benefit, but they don't print (or transfer to pdf) as red!
Then use cross-staff (shift+X), then beam them with the beam tool (shift+B), and change note stem directions as desired.
You can also remove the time signature completely - this also doesn't turn the notes red. Though you need to beam groupings as desired and not useful for the Ponchielli. But useful for plainchant - seen below with stems hidden
-Chris
