The following seem particularly useful in the process of KDE translations:
Version Control with Subversion (The book is part of SVN, so it might have been installed on your system as part of SVN's documentation.)
The overview of compiling KDE from CVS sources at developer.kde.org
The KDE Unicode Howto by Wolfram Diestel
Various information on the l10n server, especially lots of useful stuff on DocBook in general and KDE documentation in particular by the editorial and doc translation teams in the main documentation directory. Not on l10n.kde.org but equally useful in this context are the scripts and pages by Frederik Fouvry and the The KDE DocBook Authors guide by Lauri Watts.