I recommend a different tool. IXChariot. If you are trying to answer questions related to network performance then you are better off using a network testing tool rather than an application testing tool, because then you have to ensure that your application is many times more scalable than your network. Very few applications actually meet that criteria.
IXChariot also has the advantages that it is used by the WiFi alliance for certification purposes, it can be custom built into devices for use as an endpoint and you can use a separate network for test control from the network under test. So you endpoints can be dual homed with the test controlled over ethernet and your test conducted over WiFi, so you don't wind up distorting your network under test with your control elements.
Give Ixia Communications a ring. They should be able to set you up with a leased license. By the way, as a network tool it is also a lot easier to setup and use than an application testing tool.