Thank you for this suggestions, they are very useful, it's a shame but I completely forgotten about filters in the open dialog. That's more better now.
Anyway for lit converting I find a program called "clit" at http://www.convertlit.com/
and seems to be interesting, it converts lit to OEBPS. I made some testing and it is working fast but the .opf project that is saved seems to be not compatible with Ebook Publisher's own .opf .
Please detail me a little because I don't understood very well what you want to say with:
Now only if we can get access to the .tmp (html) file that gets created (and then deleted) by eBook Publisher as well as the images. I tried .epub, but the images are not stored (a bug with eBook Publisher).
I guess I missing something, (never used .opf only for creating ebooks)