Isn't the solution already in this thread?
http://www.gnutellaforums.com/showthread.php?t=66937
Set max total download connections and max download connections per file to 1 and you should never download from more then one host in total.

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Im sorry....I wasnt specific in my post. You are correct that these settings will force a download from a single host. However, in order to filter as I would like I need to know the ip address from which the file was downloaded. It seems that when I expand a tree (or download from an apparent single source) the x-alt info is traded in the header. If the intended host (ip address) doesnt offer the best source, my download moves on to another host. I then have to search through a fair amount of data until I can determine which ip address to use for a filter. Its sometimes time consuming. It would be very helpful to me if I can select a host ip in advance. If the host is not available I would rather it simply showed waiting or timed out than move on to another host.
Thanks
Dave