Or you can click the "Go into bundles" checkbox if you want to open the files from inside the editor (at least, if you're using SubEthaEdit -- I assume other editors have a similar functionality).
So you have to open them like a folder and will find the single files you need to edit inside. To do this you have to right-click the OXP and select "open package" from the context-menu.
Yes that worked. Can now read the files (and alter them to seriously bugger things up, )
)