If you followed the Softmod Any Wii guide, you should have a USB Loader channel (picture of disc and usb hd), and CFG Usb Loader. The most commonly used method is to create a wbfs folder on your usb device, and put .wbfs files in there. CFG Loader (or the other main ones) will pick them up and show them. I think you confued "pri loaders" with USB Loaders. Priiloader is something that you install that boots before your system menu. It will provide protection against updates and brick recovery options.
Once you're in CFG Loader and the game shows up. Select it. From there you should be able to open the settings and as I recall "Force PAL" will be an option in the "Video" setting.
See also the "Loading from USB" section of the softmod guide.