The bugfieldmapping command provides the ability to import or export the XML file that maps auto generated bug fields to ...

The bugfieldmapping command provides the ability to import or
export the XML file that maps auto generated bug fields to work item
fields.  The options available for each of these actions are listed 
below.

tcm bugfieldmapping /export /mappingfile:path 
                    /collection:teamprojectcollectionurl 
                    /teamproject:project [/login:username,[password]]

tcm bugfieldmapping /import /mappingfile:path 
                    /collection:teamprojectcollectionurl 
                    /teamproject:project [/login:username,[password]]