I found a wy to interrogate the statistics database directly instead of the main database which removes the 180 day issue.
If you take a look at the BIRT project site on OSCELOT (http://projects.oscelot.org/gf/project/birt/) you will be able to find more information and sample reports.
I will be posting a new version of the documentation this morning which will include how to connect to the statistics database.
The guide was written by myself and Andy Hulme from Blackboard support. If you have any questions just let me know.