There’s no Device Handler that’s been written for the Remote yet - I’m in the same boat as you.
I managed to get the device to the SmartThings hub by pressing the pair button 4 times, then holding the device very very close to the hub. [Edit: I might have also held the pair button in] Once I did that, it saw it as a “Thing”. I could then dial in to the GUI of API and change the device type between different devices; however - it doesn’t matter what device type I’m using at the moment, it can’t do more than receive the battery status.
Going forward, someone will write a device handler that will work (currently, no-one can even see messages coming back when you press the buttons!), but that’s being worked on over here: IKEA Tradfri Button -- help needed
I’m hoping to start taking a look myself, but I’m completely new at Zigbee, so I’m expecting a steep learning curve!