You need to write something like this in ffdshow:
Setmemorymax(512)
SetMTMode(3,4)
LoadPlugin("CORRECT_PATH/svpflow1.dll")
LoadPlugin("CORRECT_PATH/svpflow2.dll")
Import("CORRECT_PATH/InterFrame2.avsi")
ffdshow_source()
SetMTMode(2)
InterFrame(Cores=4)
distributor()
But I wonder what you're expecting from InterFrame? It uses the very same libraries that SVP does with 23th SVP-shader and very hard settings.