Imported message input format is always 1

When importing VBulletin messages or comments into Drupal, the "format" column is always populated as 1. This may not always be the desired input format for the message, since you might need to create a new input format that allows BBCode, for example.

Having a drop-down that lets you pick which input format to use prior to performing the import would be ideal, rather than hard-coding it to 1.