Find a large tooth cross-cut saw—hand operated. Firewood drys mostly from the end of the grain. Twenty inch length needs to season a minimum 12 month, sixteen inch usable in 6 months, and 12 inch sufficiently dry in 2 month. Multiple short lengths in a wood appliance are more problematic to obtain a sustained burn.
The average American would not be able to convert their homes in time after a winter EMP attack. Also, heating's only one problem - there would be securing water and finding food too. And dealing with violence in a world where 911 doesn't work... Decades ago I spent a year living in a log cabin in the north woods... heating with wood, and getting daily water from an artisan well some distance away... I have some idea of what it would take... and I doubt I would survive an EMP attack past the first few months.