Hi
Under windows XP, you can disable the directx plugin and use the 'Raw' plugin, this will expose multiple mice if you have them. Example, my laptop has a built in mouse, but I plug in an external usb mouse as it's easier to use when I have a desk to put my laptop on. Using the platform default plugin on windows shows 1 mouse. With the raw plugin, I get 2.
You have to disable the directx plugin becase both plugins can't capture the device(s) at the same time it appears.
To disable the default platform plugin add the property
jinput.useDefaultPlugin=false and to list the plugins you with to load, add their classes to the
jinput.plugins property, for the raw one, you want
jinput.plugins=net.java.games.input.RawInputEnvironmentPlugin. So to run the controller read test that comes with jinput, in the main directory, you should be able to run
java -Djava.library.path=dist -cp dist\jinput.jar;dist\jinput-test.jar -Djinput.plugins=net.java.games.input.RawInputEnvironmentPlugin -Djinput.useDefaultPlugin=false net.java.games.input.test.ControllerReadTest.
Under Linux it should already pick multiple mice up anyway. I'm unsure about OSX, and have no way to test, I'll try giving Elias a prod and see what falls out

HTH
Endolf