Duplicating mc's with keys

hi, im looking for some help on duplicating mc’s with keys instead of the mouse. ive been working with flash for quite some time, and i think im pretty good. i have about 13 submissions on newgroundw with descent scores, and 2 of them are even in an archive. im kinda new with actionscript though, ive been learning for about a month now. but im kinda on and off. so can anyone help me on duplicating mc’s with keys?

this is wat i have.

onClipEvent (keyDown) {
if (Key.isDown(SPACE)) {
i = i + 1;
duplicateMovieClip (_root.box, “box” + i, i);
}

thnx ahead of time.