Depending on how slow is slow... simply use 'Stretch mouse mode' (it's in the Help file)and drag out the end of your clip, or go to 'Effects' >> 'Video effects' >> 'Speed and enter a value. In either case you are limited to 2X ratio if there is a linked audio track. If you first un-group the audio there is no real limit though you will get to the stage of seeing a series of still frames. MEP 2013 can do some interpolation to smooth things out a bit; I don't know if it came in with your 2012 version.