intended/structured index

[Saalfeld, Christoph]

Hi,

I'd like to have an index in the form of

"Fehler, 20
    -Diagnose, 23, 25
    -Management, 27, 29
    -Erkennung, 22, 24
    -Behandlung, 19-21, 24"

instead of

"Fehler, 20
 Fehlerdiagnose, 23, 25
 Fehlermanagement, 27, 29
 Fehlererkennung, 22, 24
 Fehlerbehandlung, 19-21, 24"

You can see this type of index in books often.
How can I teach LyX to create an index of the upper type ?

I'm using LyX 1.1.6fix3 for Win32 on CYGWIN and MikTeX.

Christoph