setting the beamlet size in cue notes - help needed

[Janek Warchoł]

Hi,

how can i override beamlet length in cue notes?
In the following code the \override Stem #'beamlet-default-length doesn't work.

\version "2.13.45"
\include "italiano.ly"

\addQuote "viola" {
    sib4 r8 sol sol'8. fa'16 mib'8.-\trill re'16 |
  }

\score {
      <<
        \new Staff = tenorStaff {
            \new Voice = tenorVoice { R1 }
          }
        \context Staff = tenorStaff {
            \new CueVoice \with { instrumentCueName = "vla." }
            \override Stem #'beamlet-default-length = #'(0.75 . 0.75)
            \cueDuring #"viola" #UP { s1 }
          }
      >>
  }

The "\context Staff = tenorStaff" stuff is necessary (this snippet is
a part of a large project).
I know this can be done somehow because i did it once, and now i'm
trying to do it again for an hour or more with no success... :(

cheers,
Janek