I think that what he's asking is to programatically ensure that the developers in his project all specify a tenentid in their HQL query strings. If you really need to do this at runtime (it would be a performance hit), take a look at the classes in src/main/org/jboss/seam/persistence. You might be able to override one of them, then explicitly install it in components.xml.
Even better, see if there's some way to add a restriction to your build that searches java files for strings beginning with
from, then checks that they include tenentid before allowing the files to be compiled. This would find bugs at compile time, not runtime.