Killer Shortcut. But How?

HAI.i was wondering, how i can make the (space) button work like the (return) let me explain: if i press the spacebar once, it will move down once from the current line (like the return button dos as default) and if i press fast two times, it Will play from current line. so the spacebar works in two ways… and then i would like the shift button to play the pattern from the beginning (like the spacebar dos as default) hmmm… can this be done, my fellow renoise ninjas :ph34r: