Right click on clip, show keyframes, speed.
Pen tool (P), click where you want it to come in and out. Drag it down to the speed you want in between the keyframes. Drag the two sliders to how fast/slow it transitions from 100% to 40% (if you're working with 60fps footage)
A video about it. http://www.newschoolers.com/videos/watch/799766/QuickTip---Speed-Ramps-or-Time-Remapping-in-Premiere-Pro-CC
"If you aren't crashing, you aren't skiing."
Sun Valley, Idaho