Bugzilla mapping description to custom field

I am working on a complex Bugzilla mapping into a highly customized work item type with customized fields. I need to be able to map the default description (com.ibm.team.workitem.attribute.description) to a custom value (e.g., my_description). The default mapping does a great job of mapping the first Bugzilla description into the default RTC work item description but I need it to be mapped to this new/customer entry. I thought something like:

<attribute>

in the mapping .xml might work but it doesn't. I tried using "long_desc" but that doesn't seem to work either.

Anyone have a way to do this?