Classpath

[Mark]

 How can I add jars to Hadoops classpath when running MapReduce jobs 
for the following situations?

1) Assuming that the jars are local the nodes that running the job.
2) The jobs are only local to the client submitting the job.
I'm assuming I can just jar up all required jobs into the main job jar 
being submitted, but I was wondering if there was some other way. Thanks