hi,
I am also facing a similar problem. I have seen similar questions posted by others quite long ago. Sadly none of the biztalk experts have suggested anything. [:(]
Mean while I found one article that uses a different approach in handling this issue.
http://agilior.pt/blogs/bruno.camara/archive/2008/04/17/4344.aspx
But I could not get it to work. There is not much info on the type of the messages and ports.