Flex :: Encoding Key Strokes As Bits In Uint

I am trying to encode certain values that I receive from keyboard event. Basically I want to check if a certain key combination has been pressed or not, so for that I am converting the key codes into sequence/pattern and store it in an object and a value(function) against each code sequence. Now I have to use four bytes and in first byte(MSB) I've to store shift, alt, ctrl respectively and in the last(LSB) I have to store the keycode of the key pressed.

Here is the code:
private function m_encodeValue(key:String, Ctrl:Boolean = true, Alt:Boolean = true, Shift:Boolean = false):uint {
var encodedValue:uint;
encodedValue = uint(Shift) << 2 | uint(Alt) << 1 | uint(Ctrl);
encodedValue = encodedValue | (uint(key.toUpperCase().charCodeAt(0)) << 24);
return encodedValue;
}