Hi fazzi. Yes, I think you will need an infrared blaster such as the one that comes with the MCE remote. Just make sure it is a version 2 remote (see here for more info http://www.mythtv.org/wiki/index.php/MCE_Remote). On the back of the infrared receiver are two jacks for plugging in the included infrared blasters, although you will only need to use one of them to control your STB.
As far as I can tell, there aren't any reasonable options for acquiring an infrared receiver/blaster separately (without a remote), but the low price makes this a good option, even if you don't need the MCE remote.