borders for scanned prints

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I'm making a CD of my black and white work, and about 75% of it was printed with a filed out negative carrier so they have nice black borders, but the rest don't and it's an ugly inconsistency.

I've just been using iphoto for this process, and I'm wondering if it would be possible to add a little black border to the rest of these scanned prints.

Any suggestions?
Thanks!