Makeindex without sorting

Question

Can I use makeindex but without sorting? This question looks peculiar but I would like to use index while the index entries (for example \index{Peace} in the document) are already sorted correctly according to Icelandic alphabet. The reason is that xindy sorting of Icelandic (for now) is incorrect (according to this answer)

Answer 1

Your question isn't very clear but if I take the MWE from the linked question and add ascii approximations to the strings before @ then makeindex sorts as required. (I may have the sort order wrong but the idea is that if the order is A Á B then change Á to anything that sorts between A and B (say A1) and put the mangled string before @ so it is only used for sorting.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[]{makeidx}
\usepackage[icelandic, czech]{babel}
\makeindex
\begin{document}
Hello
\index{z1ari@Þari - Franz Eugen Kohler, Public Domain}
\index{z1istill@Þistill - ŠARŽÍK František, COPYRIGHT/PD}
\index{O2nd@Önd - Karney, Lee, PD}
\index{a3d@Æðarkóngur - Whitehouse, Laura L., PD}
\index{Avo1@Avókadó - Forest \& Kim [[p:2684;Starr]], CC-BY}
\index{Aud1@Auðnutittlingur - Arnstein Rønning, CC BY-SA 3.0}
\index{Asni@Asni - Zicha Ondřej, COPYRIGHT/CC-BY-NC}
\index{A1@Á - hvalur.org, CC Unported Licence}
\index{A1lft@Álft - Bukovský Jiří, COPYRIGHT/CC-BY-NC}
\index{A1lka@Álka - Jack Spellingbacon from Scotland, CC BY-SA 3.0}

\printindex
\end{document}

Answer 2

Not recommended

Just in case if someone is in need of creating an index without sorting in xindy. I am adding a number from counter to the index terms and they become a part of sorting process. We lose letter groups anyway.

lualatex mal-xindy-nosorting.tex
xindy -M texindy -M makeindex mal-xindy-nosorting.idx
lualatex mal-xindy-nosorting.tex

The generated idx looks like this:

\indexentry{1 dog@dog|hyperpage}{1}
\indexentry{2 mouse@mouse|hyperpage}{1}
\indexentry{3 horse@horse|hyperpage}{1}
\indexentry{4 cat@cat|hyperpage}{1}
\indexentry{5 bird@bird|hyperpage}{1}
\indexentry{6 girafa@girafa|hyperpage}{1}
\indexentry{7 zebra@zebra|hyperpage}{1}
\indexentry{8 jellyfish@jellyfish|hyperpage}{1}
\indexentry{9 lion@lion|hyperpage}{1}
\indexentry{10 cow@cow|hyperpage}{1}
\indexentry{11 octopus@octopus|hyperpage}{1}
\indexentry{12 ant@ant|hyperpage}{1}
\indexentry{13 worm@worm|hyperpage}{1}
\indexentry{14 wolf@wolf|hyperpage}{1}
\indexentry{15 owl@owl|hyperpage}{1}

And the content of the ind file is this:

\begin{theindex}
  \providecommand*\lettergroupDefault[1]{}
  \providecommand*\lettergroup[1]{%
      \par\textbf{#1}\par
      \nopagebreak
  }

  \lettergroupDefault{default}
  \item dog, \hyperpage{1}
  \item mouse, \hyperpage{1}
  \item horse, \hyperpage{1}
  \item cat, \hyperpage{1}
  \item bird, \hyperpage{1}
  \item girafa, \hyperpage{1}
  \item zebra, \hyperpage{1}
  \item jellyfish, \hyperpage{1}
  \item lion, \hyperpage{1}
  \item cow, \hyperpage{1}
  \item octopus, \hyperpage{1}
  \item ant, \hyperpage{1}
  \item worm, \hyperpage{1}
  \item wolf, \hyperpage{1}
  \item owl, \hyperpage{1}

\end{theindex} 

I also enclose the tex file and a preview of page 2 in pdf:

%! *latex mal-xindy-nosorting.tex
%! xindy -M texindy -M makeindex mal-xindy-nosorting.idx
%! *latex mal-xindy-nosorting.tex
\documentclass{article}
\pagestyle{empty}
\usepackage[colorlinks]{hyperref}
\usepackage{makeidx}
\makeindex
\begin{document}
The first paragraph of text.
\let\oldindex=\index
\newcount\malcount \malcount=0
\def\index#1{\advance\malcount by 1%
  \oldindex{\the\malcount\space#1@#1}%
  }% End of \index redefinition...
\index{dog}\index{mouse}\index{horse}
\index{cat}\index{bird}\index{girafa}\index{zebra}
\index{jellyfish}\index{lion}\index{cow}\index{octopus}
\index{ant}\index{worm}\index{wolf}\index{owl}
\begingroup\def\thispagestyle#1{}\printindex\endgroup
\end{document}