To score off a corner every time, kick the ball towards the goalie. When a forward gets hold of it, kick it across the goal mouth and use after-touch to bend it into the net. The computer never quite manages to work out what is going on until it is too late. When your match appears next on the fixtures screen, for example England (You) v Germany (The Opposition), instead of choosing next match, click on Exit. Now choose friendly from the main menu and choose Germany as your team. Go to the Team/Formations Screen and get all the German star players on the bench, put the forward in goal, and generally mess about with the original team selection. Now start to play the game, but escape from it as soon as it begins. Return to the League/Cup games and View Opposition (Germany). Your opponents team will still be mucked up. Using this cheat you should be able to win every match.
This cheat will allow you to play the game in slow motion (aka Kick Off 2). What you have to do is play a match and then make a substitution. Then when the player is walking off, press the 'ESC' key and you will quit the game. Start another match and you should notice that everything plays at slow speed, even the timer! To return to normal, make another substitution, but let it carry through.