First of all you right click on the footage you wish to speed up in Sony Vegas.
Then select Insert/Remove Envelope --> Velocity.
You should now see a horizontal line across the middle of your footage, raise this line to speed it up. If this isn't fast enough, then you can try right clicking on the footage again and going into properties and increasing the playback rate.
If you want to have a slow pan effect while the video is sped up, then you will need to play around with "F8" and invisible cobwebs(flying through to slow down) while recording in game. There is also a timelapse bukkit plugin which is worth looking at.
I hope this helped!