Making Data Directory movable

${SegmentFile}
Var CustomDataDir

${SegmentInit}
StrCpy $CustomDataDir "Data"
${ReadUserOverrideConfig} $0 SettingsDirectory
${IfThen} $0 != "" ${|} StrCpy $CustomDataDir $0 ${|}
${SetEnvironmentVariable} PAL:DataDir "$EXEDIR\$CustomDataDir"
!macroend

This does not seem to work.. Any suggestions?