The instructions for doing this in camera are given on page 49 of the manual. You need to be shooting in MP4 mode. At 35 mbps it records at 60 fps, but shoots in either 30 fps or 24 fps, resulting in sped up footage. At 24 mbps it records at either 30 fps (and shoots either 60 fps or 24 fps) or 24 fps (and shoots at either 60 fps or 30 fps). Basically it is shooting X frames per second and conforming it to a Y frames per second timeline.
That provides you with a number of options for either speeding up or slowing down your footage in camera by up to 2.5X either way, depending on what frame rate you choose for recording and what frame rate you choose for shooting.
You need to follow the same rules (such as shutter speed) you normally would use for a particular shooting frame rate, so if you are recording 24 fps and shooting at 60 fps (for slowed down video), you should have a shutter speed of 1/100 or 1/125.
Last edited by Tugela; 08-15-2014 at 12:27 PM.