For the basic vplug emulator without the SBCL plugin referred to by mhku, it just runs in the background of your DVB application; provided you have up-to-date keyfiles in the plugins folder, it'll work without any input from you.
Clicking on Show Monitor in the Plugin box of your running application gives you several tabs that allow you to update transponders and import keys. There's also an editor at the end that allows you to check and change parameters of channels, add and edit softcams etc.
Llew