How to setup JFlex in Idea 11


I'm trying to make a custom language plugin (following this page), for which I need JFlex. I installed the JFlex plugin, configured its paths in Settings but it still fails to compile .flex files and it says:

Command "/usr/lib/jvm/java-6-sun/bin/java -Dfile.encoding=UTF-8 -classpath ./lib/JFlex.jar JFlex.Main --charat --nobak  --skel "/home/juzna/projects/intellij-community/tools/lexer/idea-flex.skeleton" --quiet  -d "/home/juzna/IdeaProjects/intellij-latte/src/cz/juzna/latte/lexer" "/home/juzna/IdeaProjects/intellij-latte/src/cz/juzna/latte/lexer/latte.flex"" execution failed with exit code 1

I've got JFlex.jar copied in my project's lib/ dir, however I'm not sure if it's the correct location.

Can you give me a hint how you made your JFlex plugin work? Thanks