Slur under beam

[Andrew Bernard]

How do you position a slur under a beam?

Setting Slur.positions does not want to move it, which is fine, but I cannot 
find the correct override or setting.

And in this example, part of a complex multivoice score which is very dense, I 
do need the slur under the beam and above the notes. The score uses quite long 
stems, so there is plenty of room for the slur to fit.

Andrew

— snip
\version "2.19.28"

treble = {
  \clef treble
  \stemUp
  \slurUp
  \override Slur.positions = #'(1 . 1)
  g''16[( e'' dis'' b' g')]
}

\score {
  \new Staff { \treble }

  \layout {
    \context {
      \Voice
      % set unbeamed note stem lengths
      \override Stem.details.lengths = #'(5.5 5.5 5.5 6 6)
      % set beamed note stem lengths
      \override Stem.details.beamed-lengths = #'(5.5 5.5 6.5 6.5)
    }
  }
}
— snip