How to use VARBINARY with CsvBulkLoadTool

[Cox, Jonathan A]

I am wondering how I can use the CsvBulkLoadTool to insert binary data to a 
table. For one thing, which format does CsvBulkLoadTool expect the data to be 
encoded as within the CSV, when inserted into a VARBINARY type? Hex? Base64? 
Something else? Is there a way to choose or specify?

Thanks,
Jon