Hi,
Please see this thread:
http://www.vi-control.net/forum/viewtopic.php?t=20533
Basically I have tried everything I can think of to load 3rd party VST's into Vienna Ensemble but it just doesn't seem to work. I have set all the paths I can see and none of it seems to make a difference. I am using the demo licence and have already used about 7 starts just trying to figure this out.