no we have nothing pre-built nor any guidance for importing data form other sources. People have done it before but the logic will vasry of course depending on the source of data. There are various tools available that can be used to enable querying one data source and inserting it into a table in another data source.

I can tell you that back in 2004 I migrated a site from Rainbow Portal MS SQL to mojoPortal MySql using SqlYog Enterprise version. I was able to make an odbc connection to MS SQL and write a query and insert rows into MySql. The free version of SqlYog did not support this but the Enterprise version was not too expensive. It might also be possible using Aqua Data Studio, I haven't used it in a few years but it supports multiple db platforms.

The MySQL Workbench is a very nice tool for administering MySQL and migrating data. Also the Microsoft SQL Server Migration Assistant for MySQL is very helpful.