Obviously you need the IDE / JDE to develop the application. However, the simulator can be run without starting up the IDE. The IDE requires the Java 2 SDK Standard Edition. The simulator does not.
Assume you want to run the simulator on a laptop which does not have the J2SE platform installed.
First install the BlackBerry Java Development Environment (JDE) from the Blackberry site. Then copy across the program files app.code, app.cso, app.debug and app.jar into the "C:\Program Files\Research In Motion\BlackBerry JDE 4.0.2\simulator" directory on the laptop. (This path assumes that you have installed the 4.0.2 JDE).
Now run the required simulator file from that directory e.g. 7100v.bat.