What dataset did your USDS100 come with? I bought mine from Ozscan so it came with an SD card with the full dataset (Victoria, for me). To add or change anything, it was a matter of looking at how an existing system is programmed in, and take it from there.
Programming yourself is certainly the way of learning how to program the device and a personal preference, but mine was rather than tear my hair out trying to figure out how to do it from scratch then wondering why things weren't working, it was simpler to buy the SD card with all the latest data and modify/add to that as needed
http://ozscan.blogspot.com/
https://wiki.radioreference.com/index.p ... 0_FAQ_Page
http://new.marksscanners.com/SDS/100_200.shtml