Sorry: apparently they cannot even be modified in .htaccess--that was a mistake.

Assigning this task to Rui Hirokawa for fear it'd be forgotten. (Rui, feel free to reassign to me if you think it better)

I can not get the result with you.
I can change mbstring.http_output (and some others) in a script.
This is a sample script,
<?php
 print mb_http_output()."\n"; // default output encoding.
 mb_http_output("EUC-JP"); // set new encoding.
 // or ini_set("mbstring.http_output","EUC-JP");
 print mb_http_output()."\n"; // output: "EUC-JP".
?>

And, mbstring.func_overload is defined as PHP_INI_SYSTEM
in the php manual, and is not defined as PHP_INI_ALL.

For func_overload you are right--I misread.

For what matters your example: you're right too. The problem is that I was checking using what's written in the docs, i.e., that ini_set() would return false on failure:

php -q
<?php
print mb_http_output()."\n";
print ini_set("mbstring.http_output", "EUC-JP") === false;
print "\n".mb_http_output()."\n";
?>
pass
1
EUC-JP

BTW, this is really with PHP 4.2.2.

So either the first or the second statement are returning the wrong value.

On my linux box with php-4.3.1, the abobe small script works fine. Please check it again with php-4.3.1.
 
<?php
 print mb_http_output()."\n";
 print ini_set("mbstring.http_output", "EUC-JP") === false  ? "FALSE" : "TRUE";
 print "\n".mb_http_output()."\n";
// it returns: 
//  SJIS
//  TRUE
//  EUC-JP
?>

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.