If the JInput jar is placed into lib/ext, isn't it automatically granted the privileges to access whatever it needs to access?
Don't EVER put sumething into lib/ext, if don't know exactly what you are doing. There are multiple problems with this approach:
1. You may break webstart code and applets using a
different version of jinput than you
2. The dlls/natives won't get loaded from lib/ext, so you have
to put them to some system library path
3. You will have to tell your users to put the files to
various (delecate) directories on their system
(you can't acces the harddisk from a non-signed applet)
4. The applet still won't have access to native code (dlls)
when unsigned. You could completely circumvent applet
security otherwise (using win32 native file access for
example to spread viruses)
5. You would encourage ALL YOUR USERS to get problem no. 1!!!