This is where most users fail. A PKG is useless without its corresponding RAP file (the digital license key). The PS3 checks: "Does this song have a valid RAP signature?" For free DLC to work, you must install a "fake" RAP file using a tool like psnstuff or ReactPSN . This tricks the console into thinking you purchased the song.
But the cost is high. You risk your console, your PSN account, and your personal data to malware-ridden file hosts. Furthermore, Ubisoft San Francisco (the developer) relied on DLC sales to justify releasing weekly lessons, tones, and new arrangements. When players pirate these PKGs, it signals that music learning games are not profitable. rocksmith 2014 ps3 dlc pkg free
Here is the technical workflow users attempt: This is where most users fail
Ubisoft officially tolerates Custom DLC for PC users, but on PS3, it is a hack. However, it is generally safer than piracy because custom songs (usually created by fans for bands like Tool, System of a Down, or obscure Japanese rock) do not compete directly with official store sales. This tricks the console into thinking you purchased the song