AppPerfect Load Test allows users to distribute load on multiple machines to simulate better load condition for server. To distribute load or virtual users on multiple machines you need to install AppPerfect Load Test product on all those machines. A product Service named "AppService" gets installed along with product, now you just need to specify number of virtual users you want to run on that machine while creating project.
AppPerfect Load Test will take care to copy the required project on remote machine and to start test on all machines. The central controller machine will show status of all machines in the status view. Also at the end of execution it will present the consolidated results of all machines as well as machine wise results to help you identify the bottleneck or performance issues in your application.
There is no difference in installed system of central controller machine or any other machine, so you can make any machine as central controller.
You can configure the option to execute test on remote machines at Project -> Properties... -> Machine Settings.