There are several ways to do SQL imports:

1) The simplest way is to use phpmyadmin to export your listings data as a CSV, then use the csv importer to import. Note however that this will import only the listings.
2) Adapt one of the existing importers: http://scripts.webmastersite.net/wsnlinks/importers/
3) Transform all the fields of the old table via phpmyadmin to use the WSN names, remove extranous fields, export with complete inserts, then import to the WSN table and set validated=1, then regenerate counters.


If you aren't comfortable doing the above options yourself then you may purchase the import as a custom project in the services section -- ask for an estimate