I think my question really boils down to "how to convince LWP::UserAgent to keep the Cyrillic endcoding of the webpage?"
Nope, here's why :)

D:\>wget "http://www.1418.ru/chronicles.php?p=100" -O 1418.ru.p-100.wg
+et.html
--23:15:17--  http://www.1418.ru/chronicles.php?p=100
           => `1418.ru.p-100.wget.html'
Resolving www.1418.ru... 83.220.35.214
Connecting to www.1418.ru|83.220.35.214|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]

    [  <=>                                ] 9,294         38.75K/s

23:15:18 (38.75 KB/s) - `1418.ru.p-100.wget.html' saved [9294]

D:\>lwp-request -m get "http://www.1418.ru/chronicles.php?p=100" > 141
+8.ru.p-100.lwp-request.html

D:\>md5sum 1418.ru.p-100.lwp-request.html 1418.ru.p-100.wget.html
221e06fca05e17a1f4ae6382acbb39b9 *1418.ru.p-100.lwp-request.html
221e06fca05e17a1f4ae6382acbb39b9 *1418.ru.p-100.wget.html

D:\>
[download]