I think people are missing half the point.

Think of this as a different question:
"How do I change the search results on my own name?"

Yes, you could point him to a SEO document, but that may not be as applicable for an individual (or maybe it is).

What are some other techniques for "improving" the results on his name to have it come up before/instead of the one with the negative association?

Yes a good HR check should be able to distinguish between the two, but what about his new peers and co workers who want to know more about him? If a casual search engine check is going to show up with a sex offender, then it wouldn't be a bad idea to try to modify the results a bit.

Of course, worst case scenario, you could end up having your portfolio show up right next to the sex offender.
Then you will guarantee that your name will be associated as a sick criminal by the gossip pool that learned about using "the google" to check up on new people from their celebrity news mag :p

Good luck, and I hope to see some other suggestions on how to change a page ranking without spending a ton of money on it.

All right apple fanboys, lets here your response on this one.