@AndreasPetter  I had a brief chat about this with @johnynek sometime back.

Config parameters can be passed via the JobConf I think. Here is an example of how cascading-jdbc does it for JDBCTap:
https://github.com/Cascading/cascading-jdbc/blob/2.5/cascading-jdbc-core/src/main/java/cascading/jdbc/db/DBConfiguration.java

For store creation on the mappers, it looks like we'll need to pass a `StoreProvider` of some kind which knows how to generate a `ReadableStore`.