Hey KC. I hope you got this issue addressed and that is the reason for the silence.
If not, here were the steps I took:
1. Drag nPDF.prg.tns into a folder (any folder, I used the ndless folder) on the nspire.
2. Run nPDF.prg.tns. (this will register the filetype *.pdf.tns openable files, and tells the calc to use npdf.tns as the program to open them with!)
3. Drag nPDF.tns into a folder (again I used ndless folder)
4. Any pdf files you want on the calc, RENAME THEM to *.pdf.tns rather than *.pdf, and place the file on the calc.
5. Now any of these *pdf.tns filese are DIRECTLY OPENABLE through the normal browser on the nspire. So just click on the pdf file you want to open.
Note: IT IS INCORRECT to try to run npdf.tns! Doing so will just give you the error "This document format is not supported..."
Hope that works for you.