played with one hand or another

[Herbert Niemeyer]

Hello,
I like to repost (and rephrase) this question:
I like to indicate to a piano player to play some notes with the
left hand and some with the right hand. All I found so far is the 
snippet below. I changed it to better explain what I need:
I'd like the first bracket without the top horizontal line, so it looks
like a long "L".
The second bracket should look just the opposite way, like a flipped, or
upside down "L".
Can anyone give me a tip on how to archive this?
I looked everywhere in the documentation, but couldn't find an answer.

Here is the changed example based on:
http://lilypond.org/doc/v2.11/Documentation/user/lilypond/Cross_002dstaff-stems 


\version "2.11.56"
\paper { ragged-right = ##t }

\new PianoStaff <<
\set PianoStaff.connectArpeggios = ##t
\override PianoStaff.Arpeggio #'stencil = #ly:arpeggio::brew-chord-bracket
\new Staff = "RH" {
  \relative c' {
    \key b \major
    \time 6/8
    b8-.(\arpeggio fis'-.\> cis-. e-. gis-. b-.)\!\fermata^\laissezVibrer
    \bar "||"
  }
}
\new Staff = "LH"{
  \relative c' {
    \clef bass
    \key b \major
    <<
      {
          e2 \arpeggio << {e4\arpeggio} \\ {\hideNotes b4\arpeggio
\unHideNotes} >>
      }
      \\
      {
        a,2.
      }
    >>
  }
}
>>
% EOF
Thanks
Herbert