If Amarok is to be built from source the Qt Script Generator at http://code.google.com/p/qtscriptgenerator/ is required. However after going through the compile steps in the package, the following errors are encountered

make[2]: Entering directory
`/users/user/downloads/software/qt/generator/svn.080725/qtbindings/qtscript_phonon'
make[2]: *** No rule to make target
`../../generated_cpp/com_trolltech_qt_phonon/main.cpp', needed by `debug/main.o'. Stop.
make[2]: Leaving directory
`/users/peter/downloads/software/qt/generator/svn.080725/qtbindings/qtscript_phonon'
make[1]: *** [debug] Error 2

The problem was reported on http://code.google.com/p/qtscriptgenerator/issues/detail?id=3 and a possible workaround is available at http://code.google.com/p/qtscriptgenerator/issues/detail?id=39 . Downloading the patch at this URL and applying it to the qtscriptgenerator source helps address the issue.
Hope this helps