Hibernate.cfg.xml + log4j.xml?

Pessoal como eu faço para referenciar dentro do hibernate.cfg.xml o log4j ? estou pegando este erro :

GRAVE: log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version). GRAVE: log4j:WARN Please initialize the log4j system properly.

GRAVE: SLF4J: Class path contains multiple SLF4J bindings. GRAVE: SLF4J: Found binding in [jar:file:/home/junior/NetBeansProjects/SIGI/build/web/WEB-INF/lib/slf4j-log4j12-1.5.8.jar!/org/slf4j/impl/StaticLoggerBinder.class] GRAVE: SLF4J: Found binding in [jar:file:/home/junior/NetBeansProjects/SIGI/build/web/WEB-INF/lib/slf4j-simple-1.5.11.jar!/org/slf4j/impl/StaticLoggerBinder.class] GRAVE: SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.