The only ways I am aware of that allow importing work items are

• Bugzilla and CSV import. See https://jazz.net/library/article/69

CSV import is built in like Bugzilla, but there are limitations what can be done especially when recreating work item links or links to other items.

The unsupported Work Item Command Line is an alternative for the built in import, where you can create your own logic. If can create links to other items in some cases. 

basically you have to ensure that you map the column headings of your spreadsheet to the field names in the user story work item in the system.  You MUST include the Type field which is the work item you are importing into. You must also ensure that any fields that you're importing that are "enumerated" that the values match exactly e.g. High versus high will not setup correctly.  Additionally if there is any operational behaviour on your work item e.g. mandatory fields required on creation, they must also be populated in your spreadsheet otherwise they will not load.

You create your spreadsheet, save it as CSV, then you use the eclipse client (unless you're using RTC 6.0.3 or higher) to import work items from CSV.

Not sure about the linkage, you'd have to export out a sample from RTC with a link to a requirement - typically its just the ID number but you need to get the column heading right as that's what drives the "hook up"

See also Importing work items from a CSV file in the Eclipse client and Importing work items from a CSV file in the web client.