Re: \immediate\write and encodings problem

> Thanks! It works. Nevertheless I am still to prepend \string to characters:

That's caused by using the inputenc package.

Mapping input characters can be done by using either the inputenc package or by
using a tcx file. One should not combine them with the exception of tcx files
such as cp8bit.tcx. This tcx implements the "identity" as mapping and is only used
to make characters directly pintable to TeX.

You could try to use a tcx file which implements the same functionality as
  \usepackage[koi8-r]{inputenc}
and use that tcx file instead of cp8bit.tcx and the above inputenc command.

Looking at http://www.mccme.ru/free-books/p_cher.htm, I get the impression that
the file koi2t2.tcx contained in the zip file
  http://www.mccme.ru/free-books/russlh.zip
does what you need. For installation of the tcx files, copy them to the web2c
directory in a texmf tre and run texhash.

Then, uncommend the inputenc line in your latex source and try
  latex --translate-file=koi2t2.tcx ...

Thomas