adjusting vertical positions of start and end of tie

[Werner LEMBERG]

Look at this example


  \relative c' {
    \clef "alto" d'2 \tweak positions #'(8 . 4) ~
    \clef "treble" d2
  }

The `\tweak positions` doesn't work – which is kind-of expected.
However, for this very situation it would be nice if I could change
the start and end position of the slur manually.

Is there a way to do it, except faking the tie with a slur?


    Werner