Event - Players presses key alteration wanted

Ok im trying to make a trigger based on a player pressing a key but i dont want it to be the arrow keys. So i converted it to jass and tried to change it to handle a letter, but it didn't like it. So does anyone know how to change this piece of jass which takes a player pressing the down key into a letter.

call TriggerRegisterPlayerKeyEventBJ( gg_trg_Distance_Increase, Player(0), bj_KEYEVENTTYPE_DEPRESS, bj_KEYEVENTKEY_DOWN )

im know its the bit that says: bj_KEYEVENTKEY_DOWN
that needs to be changed. I tried changing the word down to W, but it didn't work.

Thnx.

everyone always says that it is possible in jass. I never saw anyone do it in jass.

From my view, the only way is to make dummy abilities with letter hotkeys and make the event when it casts the ability.