The standard way to do this is to fill out a form (either in paper or on their website) and submit it to them. Then you have to wait for them to mail you a "camera card" which they say could take up to 10 days. PennDOT charges $10 to get the camera card. Then you take the camera card to a Penndot Photo Center to have your new ID made.
If you don't want to wait that long, you can go to a "on-line messenger service" office and, for an extra fee (in addition to the $10 PennDOT gets), have your camera card issued while you wait. These offices are operated by third parties--AAA operates many of them.
PennDOT page about online messenger services