This can be done in the Rocksmith Custom Toolkit. You might need vwise too probably. Open toolkit, at the bottom there is an Import Package button, you can use that to import the psarc file and it will ask you to pick a folder to save the "artifacts" aka the files packed in the psarc file. Just make a folder on desktop for easy access, you'll be deleting it when done anyways. Now, under arrangements select the bass and click remove. Then click add and browse to the folder you created, open it, look for an EOF folder. That will contain the xml note files. Pick the bass file and click ok. You will get a popup to select the tuning. Good luck cuz I don't see that tuning in the list or I'm just overlooking it, you'll probably have to define it yourself using the "..." button. IDK what the difference is to direct you how to do that. When you get that figured out click Generate and it will make you a new psarc.