Wait until the story starts to roll, then press Up, then Down 50 times (25 in each direction). Do this before the prologue ends and start the game. You will now be able to buy as many lives as you can afford for 1000 $ each in the first shop you enter.
Get enough money to purchase all of the ''engine'' upgrades at one time (the Big Wings, Jet Engine, Turbo Engine, and Rocket Engine), and a special weapon (such as the 7-way shot). At the weapon select screen, select the SMALL wings and the special weapon. You will notice that there is NO time limit on the special weapon! Even better, a shop/select balloon appears again, and if you visit it, you can select one of the better engines (not just the Small Wings), and STILL be able to select and use a special weapon without having to worry about a time limit.