Managed to finish integrating TEIID with iReport.
Since it has been a bit of a trouble and there is little documentation around I've made a tutorial to help my memory and maybe helping others around.
Here is the link.
I've created a VDB merging an Oracle DB and a MySQL one (that contain data from excel ... long way to integrate data ...)
The version used are TEIID 6.1 snapshot and iReport 3.5.2 (Java is 1.6), the PC is a windows box, but the stuff works also in linux (had to use that one this time).
* mind the classpath it has been a pain to check it right.
* look for connector troubles at the firts sign of malfunction (there are some threads in the TEIID forum about it); it should be OK with this version, but in case of trouble is the first thing I'll look upon.
I'm really happy since now that all is tested and working can create a more useful VDB and get a bunch of data integrated and have a new view on information.
A great thanks to TEIID people for the product and the help in solving problems, hopes the tutorial can give something back.