Your are luck when you use RAD. This great tool has possibility to edit anything within dedicate ejb-jar.xml editor.
Try open ejb-jar.xml, and you will be possible to edit everything related to EJB descriptors.
WebSphere has two additional files to describe EJB 2.1
ibm-ejb-jar-bnd.xmi and ibm-ejb-jar-ext.xmi. Both of them is better to edit via RAD editor instead trying to do it manually.
For example ibm-ejb-jar-ext.xmi is:
<ejbbnd:EJBJarBinding xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:ejbbnd="ejbbnd.xmi" xmlns:ejb="ejb.xmi" xmi:id="ejb-jar_ID_Bnd">
<ejbJar href="META-INF/ejb-jar.xml#ejb-jar_ID"/>
<ejbBindings xmi:id="Session_1_Bnd" jndiName="ejbs/Authentication">
<enterpriseBean xmi:type="ejb:Session" href="META-INF/ejb-jar.xml#Session_1"/>
</ejbBindings>
</ejbbnd:EJBJarBinding>
and ibm-ejb-jar-ext.xmi is
<ejbext:EJBJarExtension xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:ejbext="ejbext.xmi" xmlns:ejb="ejb.xmi" xmi:id="ejb-jar_ID_Ext">
<ejbJar href="META-INF/ejb-jar.xml#ejb-jar_ID"/>
<ejbExtensions xmi:type="ejbext:SessionExtension" xmi:id="Session_1_Ext" timeout="600">
<enterpriseBean xmi:type="ejb:Session" href="META-INF/ejb-jar.xml#Session_1"/>
<structure xmi:id="BeanStructure_1" inheritenceRoot="false"/>
<beanCache xmi:id="BeanCache_1" activateAt="ONCE"/>
<internationalization xmi:id="BeanInternationalization_1" invocationLocale="CALLER"/>
<localTran xmi:id="LocalTran_1" boundary="BEAN_METHOD" unresolvedAction="ROLLBACK"/>
</ejbExtensions>
</ejbext:EJBJarExtension>
So, I suggest to use RAD editor for to change EJB 2.1 descriptors.
If your editor doesn't work correctly - you cannot see wndow with most of proterties dividet init tabs, sections. YOu may have ruble with editing EJB descriptors. Try to right click on the ejb-jar.xml and open it with specialized editor (I don'n remember its name, but it is not "xml editor" or "System Default")