I was mucking around with PSArc, but got tired of the command line, so wrote a little tool.
It is essentially just a simplified version of PSArc.)
Just drag PAK files on to PSArcTool.EXE to extract.
Drag other file(s)/folder(s) on to create a PAK file.
It's not real intelligent, but hopefully helps.
https://github.com/periander/PSArcTool