In order to successfully compile and use KBFX, you need at least KDE 3.4.X and also you need:
Cmake - min. version 2.4.2
KDE3 and Qt3 sources - header files/devel packages
Strigi - min. version 0.5.1 - this package is OPTIONAL and is used for files inline search
You can find the most recent KBFX's list of changes at KDE SVN.