The poster is attempting to get around how Google will detect and downgrade duplicate content on the same IP address. If Google sees the same content but on different Class C's, it won't see it as the same content and will spider it as original.
It's a trick of *cough* internet marketers. *cough* *cough*
Most hosters can and will supply you with additional IP addresses. There's usually an extra fee and you may have to justify the need for them.
Additional sites usually isn't a justification though (I know it won't fly with me) and you can have many sites tied to a single IP address. Usually you'll only get them if you need to provide your own DNS servers, need to install an SSL certificate, etc. You mind as well ask your hoster though. They still may be willing if they have extra.
To be honest though, if the spiders detect that those 5 addresses are behind the same router, it'll still see them as being on the same box.
Considering that this is Black Hat SEO, I'm marking this thread as a modlook and suggesting that it be closed. I really don't think most of us want to go down this path and suggest we let this one slide.