Where to put a .jar file in an exploded EJB module

Where to put a .jar file in an exploded EJB module

I am deploying a JMS module to work alongside a servlet application. While
I am writing (and testing and rewriting) my module, the module is not
stored in a JAR file; it is in an exploded directory doubling as an
Eclipse project directory. (In the production environment, it will be in a
jar.)
My JMS module does logging with log4j. My question is: where do I put the
log4j.jar file so my EJB can find it? I tried various locations, including
a directory named lib/, but nothing seemed to work. (I could tell Eclipse
to find it in any of half a dozen places.) I eventually resorted to
putting it in the server domain lib directory (domains/my_domain/lib),
which worked for my JMS module, but messed up my servlet module's access
to the data sources - I kept getting a NotSerializableException.
If it makes any difference, I'm using Eclipse (Juno) to develop, Weblogic
10.3.5 to run and test.
Thanks.