Thank you all for the pieces of advice.
Formerly I installed VL 6.0 Light, then, by means of Gslapt I installed OpenOffice that, unfortunately took with it a lot of dependencies (some of them Gnome and KDE related), so, as I want the system as light as possible, removed OpenOffice by means of slapt-get and all the other depending packages by means of removepkg (one by one), but, as a result, I lost the GUI (only the TUI worked). In order to fix all that I had to install OpenOffice and all the stuff I don't want again. But very unsatisfied of that all I installed VL 6.0 Light again and, in doubt I could make some error using Glslapt just for downloading OpenOffice package without installing it immediately (a box to be checked for it), I decided, in this case, not to use the repository.
However, among the OpenOffice RPM packages that I downloaded from OpenOffice Site, there was one for the desktop integration, too. I transformed it into tgz one, installed, and everything is all right now, IceWM's menu included (and now I can also launch OpenOffice by terminal without typing the whole path but just 'soffice').