You can't. There is a rip kit for it which you're supposed to be able to use, but it SUCKS BIGTIME!!! It doesn't completely work. Your only bet is to either mess w/ the rip kit yourself until you come to realise it actually DOES NOT work or you can d/l the torrent. I downloaded the torrent to see what I could get, then bought the game once I realised it was worth keeping. I have my WRC World Rally Championshit at like 340-380MB region. NO COURSES CUT OUT, EITHER. I think it [torrent] was done by pSyPSP. He rocks! That's your only option. Otherwise, have fun trying to get that giant data pack open. Search Google for this EXACT phrase and you should get some good leads: "PSP World Rally Championship rip kits" try variations on that as well. You can check here, too:
go to the bottom of the page (b/c the ones on the page that comes up are all 1.50 games) and click on the bottom RIGHT link. It will lead you to the rip kits page @ ps2nfo. Look around there.
Good luck. You'll hate the rip kit in less than 5 hours from now if you find it! :D