I had trouble using the -userExtensions parameter in my RC batch file for including user-extensions. I also had trouble processing the instructions in the selenium documentation (found here: http://www.seleniumhq.org/docs/08_user_extensions.jsp#using-user-extensions-with-selenium-rc).

Instead of all the developer jargon, I simply cracked open the selenium-server-standalone-2.25.0.jar file using WinZip, and followed these instructions: