This article shows you how to add variables to the user-extensions.js file for use in your tests. You have to declare a function first, then call that function in your test to access the varaibles.This method can be used in both the IDE and RC versions of the user-extension file.
So, open your user-extensions.js file and add the following:
Selenium.prototype.doLoadParameters = function()
storedVars["machine"] = "W7M-134766";
storedVars["whoAmI"] = "RC";