Go to the Player vs. Player character select screen, then hold L + R on both controllers for a few seconds. If you did it right, the question marks (?) at the bottom of the screen will be replaced by bosses.
After the title screen select 1 player game, then the third selection, then the second and enter the following chain.
Enter these at the 1P vs. password screen. When it says ERROR! keep pressing the B button to backup to the menu that says new game and password and select new game. Choose a difficulty level and start the game. Now when you loose it will say you have 43 or 90 continues.
In Time Trial, you get progressively more and more points for larger chains until the 13x chain. However, if you keep a chain going any longer than the 13th link (x?), you don't get any chain-link bonus points. For this reason, you should never let a chain go past the 13th link in time trial.