I'm no expert, but ...
It looks as though you can switch off rate limiting altogether in the application/config/config.php file. The rate limit setting is right at the end of the file.
Alternatively, the rate_limit() function is defined in application/helpers/rate_limit_helper.php. It takes 3 parameters: the IP address, the number of requests (default 100), and the duration (default 120 seconds). You should be able to supply different parameters in the constructor for the EA_Controller class.
Hope this helps.