MyEclipse 3.8beta-1 supports struts modules. For modules you need to use the “Open with…” context-menu action on the module file.
The issue is that Eclipse does not yet provide a mechanism to associate a complex file naming pattern with editors (current support limited to file extension and literal file name). Thus, the current association limits ME to association of the StrutsConfigEditor as the default editor for files named “struct-config.xml” and as an alternative editor for files with the “.xml” extension. We are currently researching other mechanisms but most require modifying the Eclipse platform.
Notice: From your post I don’t believe ME is currently parsing the concatenated module names from the config parameter of your web.xml file correctly. If you hit a snag with this, the workaround is to separate the module declarations in you web.xml using the approach:
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>config/modB</param-name>
<param-value>/WEB-INF/struts-config-modB.xml</param-value>
</init-param>