hit it with a bit of wd-40 (both side - near the shoulder and where the lockring normally is)
wrap the whole length of the chain on the chainwhip around the cog (you can try and add more links if you need to).
get it nice and snug.
make sure you are applying pressure in the correct direction.
get a hammer and TAP the whip handle
take your time

i had a similar dilemma this weekend. and I still had time for a nice frosty Kitachino 2005 Celebration Ale.