I am really starting to hate people who post and have no clue how game development and porting actually work. Dont we have like 15 pinned topics about that in these forums?
Bomberman world, the one you can download for GP32, was not a conversion. For that he would have needed the source code to the PSX version. He simply wrote a bombman game engine and used the PSX bomberman graphics instead of designing his own.
To get a GP32 native Tony Hawk you would either need the source code to the original engine (very unlikely to happen), and port it to the GP32 (which I doubt would be very fast). Or write your own engine from the ground up and use the Tony Hawk models and textures. (like the guy did for bomberman).