Polyphonic Tablature

[Nigel Tao]

Hiya.  Lilypond newbie here - so I'm probably mangling the terminology...

I am trying to re-use the same (polyphonic, separated by \\) notes for
both a regular staff and a tablature staff, but the tablature and \\
don't seem to be playing nice, so instead of typing out the notes just
once in a macro and invoking it twice, I have to re-jig the two voices
as a single-voiced chords in the tablature version, ending up with an
inelegant duplication of effort.

Picture of what I want to achieve:
http://nigel.tao.googlepages.com/polyphonic-tablature.png

What I'm doing:
----------------------------------
{
\new StaffGroup <<
\new Staff {
        \key d \major
        \clef "G_8"
        <<
        {
                fis'8 a d' fis'
                e' fis ais <cis' e'>
        } \\
        {
                d2 cis
        }
        >>
}

\new TabStaff {
        \override TabStaff.Stem #'transparent = ##t
        \override TabStaff.Beam #'transparent = ##t
        <fis' d>8 a d' fis'
        <e' cis> fis ais <cis' e'>
}
> >
}
----------------------------------

What doesn't work
----------------------------------
notes = <<
        {
                fis'8 a d' fis'
                e' fis ais <cis' e'>
        } \\
        {
                d2 cis
        }
        >>

{
\new StaffGroup <<
\new Staff {
        \key d \major
        \clef "G_8"
        \notes
}

\new TabStaff {
        \override TabStaff.Stem #'transparent = ##t
        \override TabStaff.Beam #'transparent = ##t
        \notes
}
> >
}
----------------------------------

Trying the second way, I get an empty TAB staff and doubled notes on
the regular staff.  If I take out the \overrides (even though I really
want to hide the stems and beams), then I get four staves, of which
the second one (TAB) is empty.

Cutting out the << \\ >> "works", in that I get the same notes exactly
once on each clef, but that isn't the music I want to write.  :-)

I was just wondering if I'm doing something wrong or whether what I
want to do is just not easy?  I am on version 2.6.3, if that matters,
since that's what my distro gave me...

thanks,
Nigel.