how do i make a character move when a key is pressed but not holding the key?

[SuperGibaLogan]

i am making a pac man recreation in flash, and i need to make the controls for pac-man, i want him to move forever when i press a key, but not holding it, so, can anyone give me the script for that? im using macromedia flash 8, and the actionscript version must be actionscript 2.0

[Eccy]

I'm currently working on my own Pac-Man game. My problem at the moment is whenever my character hits an item, it lags LOL!

var PC01_ACCELX = 0;
var PC01_ACCELY = 0;

function onEnterFrame()
{

_root.PC01._y += _root.PC01_ACCELY;
_root.PC01._x += _root.PC01_ACCELX;

if( Key.isDown( Key.UP ))
{
_root.PC01_ACCELY = -1;
_root.PC01_ACCELX = 0;
}

else if( Key.isDown( Key.DOWN ))
{
_root.PC01_ACCELY = 1;
_root.PC01_ACCELX = 0;
}

else if( Key.isDown( Key.LEFT ))
{

_root.PC01_ACCELY = 0;
_root.PC01_ACCELX = -1;
}

else if( Key.isDown( Key.RIGHT ))
{
_root.PC01_ACCELY = 0;
_root.PC01_ACCELX = 1;
}
}