I have the same unit, and I just take out the 2 x AAA batteries and keep them in a plastic box (I use mertrado cases that ship with Sanyo Eneloops) and only insert them when I'm using the remote.
There is a way to use the receiver part without even switching it on - just tested it with my 7D - and it will trigger the shutter switched On/Off.
I have the MC-36R with C3 connector and there are 2 components the 2.4GHz receiver (works either on the hotshoe or in your hand) + the timer RC unit with LCD which requires the 2 x AAA batteries to operate.
Mine works Wireless or Wired, but also you can just use the receiver part on its own, as a basic shutter button.
Edit: just tried the other part - the RC with LCD with NO BATTERIES installed and it acts as another shutter button, but at the end of a cord. So yes will work without the batteries, you just won't have any of the timer/interval functions - if you need them, but the batteries back in.