I have one of those sensors and it is working pretty well. Internally it uses COM1 (4800). With the demo file from examples, you must connect the sensor to COM1 (it is hardcodded into the driver)
I use Arduino 1280 with Arduino 1.0.1 IDE
The test program is:
//############test for Serial1 in arduino1280,arduino2560#########
#include "Irdirection.h"
void setup()
{
Serial.begin(9600);
}
void loop()
{
irdirection x;
char a=Serial.read();
int w=x.fire(a);
Serial.println(w);
}