Compress the front shocks about halfway. Strap from both sides of top of fork to front of bed. A Chevy S 10 will fit a Speedmaster with the tailgate down*. Believe it or not, these two front straps will offer 99.9% of what you need to secure the bike, but another two straps on the back of the bike are a good idea. I suggest transport in nuetral, so slight movements aren't pounding on the driveline, but either way is probably fine.

*Find a way to make the tailgate stay secured. Most are designed to come off the vehicle.