Argumentos en función onSuccess - Prototype

new Ajax.Request('testurl',{
method: 'post',
parameters: {param1:"A", param2:"B", param3:"C"},
onSuccess: mySuccess('myValue1', 'myValue2'),
onFailure: fnFail
})
function mySuccess(param1, param2){
return function(response){
alert(param1);
alert(param2);
alert(response);
}
}