Manually controlling beam positions

Beam positions may be controlled manually, by overriding the positions setting of the Beam grob.

\version "2.24"

\relative c' {
  \time 2/4
  % from upper staff-line (position 2) to center (position 0)
  \override Beam.positions = #'(2 . 0)
  c8 c
  % from center to one above center (position 1)
  \override Beam.positions = #'(0 . 1)
  c8 c
}