WebKit WebScripting Protocall callbacks with multiple parameters?

Question

Hey I've registered my object and function selector to get callbacks from javascript when the function is fired.

This all works fine for functions with a single parameter, how can I receive callbacks for functions with multiple parameters?

So far keeping the syntax the same gets my function to fire, however the object passed in is always a WebUndefined.

Javascript

myObject.testFunction( a, b, c );

Objective-C

if( sel == @selector( testFunction: ) )
        return NO;

-(void)testFunction:(NSObject*)parameter
{
    NSLog( @"JavaScript: %@", [parameter description] );
}