The PHP-Nuke HOWTO started also as a translation. You can read how it all started in PHP-Nuke book translation thread at nukeforums.com.
The best way to do the translation would be to install the LyX. Chris still uses an old version (1.2.0) of it, but you could try the newest one and
we will see if his document processing scripts still work.
The process is the following (see, for example, Greek Translation of Php-Nuke HOWTO and New language translation howto):
You take the LyX version of the book from the Formats section (Section 1.2), you do the translation in LyX, then send it to Chris Karakas (chris at karakas-online dot de).
Chris will use his scripts (Section 1.8) to export the LyX document to SGML, correct the SGML that comes out of LyX, then produce all other formats, as in
The advantage of this method is that you only need to translate the words, leaving everything else (like "environments", SGML tags etc.) untouched. This way paragraphs, admonitions (see Section 1.7), callouts (those small numbers in circles that you see in some code examples, as in Section 3.7), code environments etc., all
remain intact - and you don't need to recreate them.
We are in search of available volunteers to translate this book in as many languages as possible. In the case you are interested in translating this book, write to chris at karakas-online dot de,
or PHP-Nuke HOWTO. Be prepared for months of hard work, as this is 500 pages of printed material!