OpenOffice used to have a LaTeX export functionality, which was later removed, I guess. Nevertheless, there is a LaTeX writer:
sudo apt-get install openoffice.org-writer2latex writer2latex
Or, if your distribution uses LibreOffice, use
libreoffice-writer2latex instead of the above.
Just confirm all messages with
y. After installing, you can use it with
which will create a
.tex file with the same name. The formatting is pretty basic, but I think it gets the job done.
If you wish to edit it in Lyx after that, just concatenate the commands, something like that:
w2l your-document.odt && /usr/bin/env lyx your-document.tex &
I tested the conversion on Ubuntu 11.04 with the default LibreOffice installation