Here is a switch mod for what you are trying to do...
http://www.satelliteguys.us/threads/174802-Naughty-Mods-II-4x8-Switch-with-All-18V-outputs
Post a few photos of the feedhorn and waveguides. Likely that you could remove the polarity trap and install a voltage polarity switching or a bandstacked LNB.
http://www.satelliteguys.us/threads/174802-Naughty-Mods-II-4x8-Switch-with-All-18V-outputs
Post a few photos of the feedhorn and waveguides. Likely that you could remove the polarity trap and install a voltage polarity switching or a bandstacked LNB.