Scarab can generate tab-separated exports of values. JIRA's CSV importer should be able to import these, because the CSV importer lets one specify a delimiter character. However it looks like JIRA may be trimming the entered character for whitespace (killing my entered tab), since the generated properties file has no mention of a separator char:

1. written by PropertiesConfiguration
2. Tue Mar 14 10:53:57 EST 2006
   existingprojectkey = TP
   importsingleproject = false
   importexistingproject = true
   mapfromcsv = false
   field.Issue type Issue ID Assigned to Priority Resolution Status Summary = summary

Attached is the sample file I'm trying to feed to the wizard.