Hold CTRL while dragging the right edge of the clip.
or
right click clip | Properties | playback speed (set to desired point
or
Right click clip, | Insert Envelope | Insert Velocity Envelope. Use this envelope to ramp speed to desired point. A value of Zero is a freeze frame, and negative values will reverse the clip.
Becareful to have Vegas 9.0b update installed. I had a lot of problems with the Slow motion features in the earlier version of V9.0. The rendering came out jerky and lost the fluidity of slow motion. V9.0b has fixed that issue.