I have a DataSet with a query like this:
select s.name, w.week_ending, w.sales
from store s, weekly_sales_summary w
where s.id=w.store_id and s.id = ?
FYI: the BIRT World article should work (I wrote it) but that was an earlier solution to the problem.
We have created an open source plugin that you can add to BIRT that has a much cleaner solution to this problem. The Bind Parameters function in the birt-functions-lib provides a simple way to do multi-selects from multi-value parameters.
If you are still interested have a look at the birt-functions-lib project on Eclipse Labs.