Draw line between fingerings, but how does this go?

[Pieter Terpstra]

Dear readers,
Trying to draw a line between the numbers, copied some code but don't know 
exactly what the commands do.
Trying to raise the line so that it fits nicely between the ones but don't know 
how, have tried the \raise command 
here without success.

Anyone?

Thank you so much in advantage!

\score {
  \relative c' { \time 2/4 \key d \minor
  <f' a-1>16<e g\finger\markup\concat {
      \hspace #.2
      \with-dimensions #'(0 . 0) #'(0 . 0)
      \override #'(thickness . 1.5)
      \rotate #-2
      \override #'(on . .8)
      \override #'(off . .4)
      \draw-line #'(-1.5 . 0)
      %\raise #'10
      \hspace #.2 "1" }>8<dis fis-1>16<f a-1>8<e g-1> 
  }
}