The first step would be to try and use a code set that is close. Like the Harman AVR340 for instance. It's rare for a manufacture to drasticly change a code set for each and every model and year. The odds are that power and input commands for Harman receivers have been the same on most models for several generations.
If something isn't in the list at all you can always create a new device in the database and learn all the codes off the origional remote into the software and then map the functions to your pronto layout as you see fit.
Also you can import alternate databases into Pronto Edit. Here is a link to one from "only 1 remote"
[Link: onlyoneremote.com] it mainly deals with current and the most popular models but there might be something in here you can use. (the link to download is at the bottom of the page under the logo "Database")