In the J2EE perspective, you can drill down on the EJBs option to get to your EJB. Double click it and another editor will open. That editor shows the remote JNDI name on the right hand side. The local JNDI name is the remote one prefaced by "local:ejb".
An alternative way to find the JNDI name is to drill down using the Universal Test Client. However, this requires the server to already be on.
Edited to add that this assumes you are using WSAD 5.X [ July 27, 2005: Message edited by: Jeanne Boyarsky ]