Requirement is to make a link label and description editable at runtime. In order to achieve that I used the ComposerOverrideBundle to edit the text resources at runtime. The approach worked perfectly and I am able to edit the required text.
However is there any way to manually access the ComposerOverrideBundle like we do with PortalBundle, so that I can add the key value pairs to make some text appear on the portal the 1st time I run it.
Sorry was my mistake not read about you want to change manually ComposerOverrideBundle.xlf.
This bundle is packaged internally with Composer libraries and you can't change it manually.
For your requeriment probably you need to register and create your own OverrideBundles than can be changed at Runtime through resource-string-editor or manually exporting MDS and importing it.
For more information read: http://docs.oracle.com/cd/E25178_01/webcenter.1111/e10148/jpsdg_page_editor_addconfig.htm#CHDBJCDF