You should be able to install the backlit keyboard with no problem. Here's the part: http://www.ifixit.com/MacBook-Parts/MacBook-Unibody-Model-No-A1278-Upper-Case-Backlit/IF160-001
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Here's how to put it in: http://www.ifixit.com/Guide/Repair/Installing-MacBook-Unibody-Model-A1278-Upper-Case/792/1
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As far as I know, the whole top has to be replaced.
You should be able to install the backlit keyboard with no problem. Here's the part: http://www.ifixit.com/MacBook-Parts/MacBook-Unibody-Model-No-A1278-Upper-Case-Backlit/IF160-001