this may be a bad idea, someone speak up if it is...

i once ended up working on a wheel on which someone had installed track nuts that didn't match the threading of the axle. after trying a bunch of different methods, i eventually was able to remove them by gripping the cone on the same side with a cone wrench and using that as counterpressure as i loosened the nut. it worked fine in my case, but i guess that this could potentially damage the bearings if the cone gets torqued down too much in the process.