WARNING: This method is only a workaround for those of you who can't reconfigure your HTTPD daemon and should be avoided when possible (I repeat, this method is not recommended). Although this method is standard and should be handled by all related soft, it may cause some trouble for a proxy and intelligent cache or pages will appears in the right character set only when loading was completed. Much better variant is the Method that requires HTTP daemon actions, but it can be unavailable in some cases (e.g. if you have mirrors of your page abroad and can't control remote httpd).
What you need to do is to insert the following tag into the <HEAD> section of your document (as early as possible):
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=KOI8-R">
This tag as described in the Internationalization of the Hypertext Markup Language (RFC 2070). Of course your browser needs to know about KOI8-R character set itself, too. Please also note that charset from the HTTP header have priority over META charset.
According to the "HTML5 The meta element" you can use the tag mentioned above or the short form:
<META CHARSET="KOI8-R">
To check if your browser supports this method, set its default encoding to ISO8859-1 or Western and load this example, then you'll see the Russian text in case this method is supported or some junk ISO8859-1 encoded text in case it isn't.
To the beginning of each style file (*.css) add:
@charset "koi8-r";
To specify encoding of text files (*.txt) and Javascript (*.js) scripts try the same method as for external resources handling.