"Hi, is there background information on this subject?
How does one go about doing this?
Yes, there is some
information, around the globe.
Your best way would be to explore an American partner of USPS, such as Zazzle, who also offers you the possibility of having your own "store", on the website of Zazzle.
Here's an example of basic Q&A about Zazzle personalized stamps ("customized postage"), from a third party website (perfectpostage.com):http://www.perfectpostage.com/faq.html