CSV Change Import for Candidates?

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My company tests candidates extensively and we record their scores.  Prior to my arrival, the test scores have been recorded in a text box, instead of an integer box, which makes it difficult to search within a range of test scores.  In order to set up this functionality, I would need to change thousands of records manually.

Is it possible to import changes to candidates if I have a column for the candidates' codes, much the way it works for Requisition imports?

Thanks in advance for any assistance!