personally id stick with your hub as it is.. its a seriously bad idea to run front freewheel on stock... doesn't feel half as good as a proper hub.. (hense why i went back to a king)... its alot of work for so many problems...
but its pretty easy to lock out your hub... just put hot glue into the internals.... or you can put a spot of weld on the outside of the freehub....
but seriously..... stick with your hub.... for the sake of your face... and all the problems it will cause you