I found a cheat mode in the game while doing the high score save routine. No doubt this will appear on all the other cheat sites with credit removed
On the title screen, type in YOUVEHADTHISPLACEREDECORATED
and then hit enter and start retyping it again. After a few keys it will fade in a blank screen and say "I don't like it!" and the cheat mode is active.
Infinite lives are now yours and keys 1-4 jump to relevant levels.
There may be other keys but that's all I've noticed so far...