chord duration

[Christian Henning]

Hi there, another problem. I hope people don't get too impatient with
me. I try to figure out how to define a chord notation that doesn't
quite fit into the normal mode. Please consider the following working
code example:

\version "2.12.2"

#(ly:set-option 'delete-intermediate-files #t)  % deletes the .ps file
automatically

<<
  \new ChordNames {
    \chordmode {
      g1 | g1:sus4 | g2 g4:sus4 |
    }
  }

  \new Voice \with {
    \consists Pitch_squash_engraver
  } \relative c'' {
    \improvisationOn
    g4 g g g
    g4 g g g
    g4 g g g
  }
>>

Inside the third measure, how can have the G chord last for 3 quarter
notes? The g:sus4 is suppose to be on the last quarter note.

Thanks a lot,
Christian