(Easy?) Change LANG= and LANGUAGE= to something else at HDD

In short, my KDE desktop is English, and all KDE control center settings are set to English (switching them back and forth does not help), but in the command line LANGUAGE=jp and LANG=jp_JP, correspondingly some programs I run from KDE desktop display their GUI in Japanese. What is the primary place to fix these LANGUAGE and LANG (and other environment variables I may miss)?

In not-so-short I downloaded Knoppix image from Japanese site, booted it with lang=en (it was all English when working from CD), ran knx2hd and got what is descrived above on HDD. Not that I completely could not read Japanese, but still English would be better for me :)

First, apt-get localepurge & remove support for all unwanted languages. Then, edit /etc/init.d/knoppix-autoconfig to set the default language to english. I think if you have done a Debian type hd install it is knoppix-hdautoconfig instead of knoppix-autoconfig; check with /etc/rcs.d/ ; the startup & config files which are used are listed there. Finally, you can remove the alternate language support files from kde with apt-get remove kde-i18n-ja kde-i18n-de etc. apt-get remove kde-i18n* will remove them all except english.
This may still not work completely; Knoppix uses special de-en versions of openoffice & mozilla which occasionaly revert to German when you least expect it. These have to be apt-get removed & replaced with standard versions. Don't know if this is true of Japanese versions though.

Thank you, in fact lang=jp was left in lilo.conf boot params. Removing it fixed the problem.