another word for twitch i guess is shake.

move_vec[0] = (key_w - key_s)*MY.WSpeed *time; <--- all this is doing is setting the move_vec[0] array to the value of (key_w - key_s)*MY.WSpeed *time...
it's the same as if you would set a value to a variable..

For example:
var x;
x = 5;

All I did was set the variable x to the value of 5... now I need to do something with this variable. Try using c_move... incase you have no idea what's going on here it is:

c_move(my,vector(move_vec[0],0,0),nullvector,GLIDE|IGNORE_PASSABLE);

put the above code anywhere inside the player_walk() function and it should work... do this:

Code:

---

FUNCTION player_walk()
{
move_vec[0] = (key_w - key_s)*MY.WSpeed *time;
c_move(my,vector(move_vec[0],0,0),nullvector,GLIDE|IGNORE_PASSABLE);
...

---

It sounds to me like you have little to know clue of what is really going on here. Do you know lite C or WDL? If not then wet your feet with the basics first, or else I promise you, you will never get multiplayer.