Create a second user account on the PS3, and set the region as the one you want to get items from. That way, when you go to the PSN Store, it will show the items for that region.
I did this very thing when the Killzone 2 demo came out. It was only available in Europe, UK, etc. I just made another user, set the region to "Ireland" and downloaded away. Granted, this was a demo, not a purchase, but I wouldn't think it would be any different.
Simply download and install the Media Go application to your PC and browse PlayStation Store right from your desktop! After you've completed downloading your favorite games, movies and TV shows, connect your PSP system to your PC using a standard USB cable, and transfer your downloads directly to your PSP system.