(1) Install a Java Virtual Machine on your computer
(2) Download the vmServices.jar from the SCEC/CME Web Site
(3) Invoke the VM Server using the command line client as follows:

Examples:
 
java -jar vmServices.jar // will show high-level usage information

java -jar vmServices.jar -help <operation> // will show parameters for op

java -jar vmServices.jar -h http://epicenter.usc.edu/axis/services/velocityService -o available // will list available VMs on this server.

java -jar vmServices.jar -h http://epicenter.usc.edu/axis/services/velocityService -s cvm/v3_0 -o vcorners --slat 34 --slon -118.5 --sdepth 0 --elat 35 --elon -117.5 --edepth 10000 --deltax 0.25 --deltaz 500 -f velocity.volume 

will get velocity values from service at epicenter.usc.edu from the version 3.0 cvm for a volume defined by the corners 34/-118.5/0m, 35/-117.5/10000m, and with horizontal grid spacing of 0.25 degrees and vertical spacing of 500 meters, putting the result into a file named velocity.volume.

leaving out the -s flag will query the service for availableVMs and prompt for a choice.