You will need to use timeremapping to accomplish what your looking to do.
Apply timeremapping to your clip.
Add a new keyframe at the point in your clip that you want it to pause at.
Copy and past that keyframe to the frame in front of it.
Now move the keyframe at the end of your clip down one frame.
You can now grab your last two keyframes and pull them down, creating a freeze frame of the space inbetween the 2nd and 3rd keyframes.
(make sure to pull the end of your clip out)
Hope this makes sense. Im tired and my brain seems to be running kinda slow.
(to have it pause at the beginning, just apply time remapping and then drag both keyframes down to the point where you want the clip to start playing.)