Showing rpm messages before rpm completes

During an install, some rpms create terminal output as the %post 
processing progresses. This is seen as it happens when using the rpm 
command directly, but yum appears to buffer it all up and spit it all 
out once (the %post) processing is complete.

Does anyone know how to get yum to show this output as it happens?

Thanks.
-- 
-Eric 'shubes'