Here's a trick that lets you use existing J-League players but assemble a phantasy team with them. Select the J-League Mode, then, at the Mode Select screen, press C-Left. This will bring you to the Option Mode, where you can edit your team.

You can now enroll this team in a World Tournament by pressing C-Up at the Mode Select screen. Select "World", then Sekaitaikai".

After you have beaten the J-Leage Mode, create an original team in Edit Mode. Now enter the Tournament Mode and enter the first four letters of the tournament as "ha-do-so-n" (Hudson). You will now be able to play on a snowy field. If you save your data after winning this tournament, you will be able to use the White Stadium in all the other modes, too.

Press C-Up (x4), C-Right (x6), C-Down (x2), C-Left (x2) at the title screen. (A tone confirms correct entry.) Enter options screen to access more difficulty settings.