6
You could copy the module tables (see /mysql/mysql.sql), but that are not the only module data that you need. The other data are buried inside the other XOOPS database tables as for permissions, notifications, etc or even comments.
Some modules can cope with the lack of these data and recreate eg permissions etc, but some don't.
I still assume that making a copy of your old site and then upgrading XOOPS, would be the easiest way.