You can just use the predefined engine variables (joy_*), like Spuperku said. Maybe this will help you:

Code:
//XBOX 360 CONTROLLER INPUT////////////////////////////////////
var XBOX360_get_deadzone(var axis)
{
	if(axis < -0.5){ return((axis+0.5)*2); }
	else if(axis > 0.5){ return((axis-0.5)*2); }
	else { return(0); }
}

#define XBOX360_BUTTON_X 258
#define XBOX360_BUTTON_Y 259
#define XBOX360_BUTTON_B 257
#define XBOX360_BUTTON_A 256
#define XBOX360_BUTTON_LB 260
#define XBOX360_BUTTON_RB 261
#define XBOX360_BUTTON_BACK 262
#define XBOX360_BUTTON_START 263
#define XBOX360_BUTTON_LEFT_STICK 264 
#define XBOX360_BUTTON_RIGHT_STICK 265
#define XBOX360_TRIGGER_LEFT maxv(joy_raw.z/255,0)
#define XBOX360_TRIGGER_RIGHT abs(minv(joy_raw.z/255,0))
#define XBOX360_STICK_LEFT_HORIZONTAL XBOX360_get_deadzone(joy_raw.x/255)
#define XBOX360_STICK_LEFT_VERTICAL XBOX360_get_deadzone(joy_raw.y*(-1)/255)
#define XBOX360_STICK_RIGHT_HORIZONTAL XBOX360_get_deadzone(joy_rot.y/255)
#define XBOX360_STICK_RIGHT_VERTICAL XBOX360_get_deadzone(joy_rot.x*(-1)/255)