\version "2.18.0"
%#(read-enable 'r6rs-hex-escapes)


\paper {
  #(include-special-characters)

  #(add-text-replacements!
    '(
      (":a" . "\u00E4" )
      (":A" . "\u00C4" )
      (":o" . "\u00F6" )
      (":O" . "\u00D6" )
    ))

}

Ms = \relative c' { a4 b c a }
Ls = \lyricmode {
  åäöÅÄÖ
  \markup { \concat { \char ##x00E5 \char ##x00C5 \char ##x00E4 \char ##x00C4 \char ##x00F6 \char ##x00D6 } }
  &aa;&AA;&:a;&:A;&:o;&:O;
  fin.
}

\score {
  <<
    \new Staff \context Voice = Vs { \Ms }
    \lyricsto Vs { \context Lyrics = Ls { \Ls } }
  >>
}