EC2 - Create Instance params for javascript aws sdk

var params = {
     ImageId: 'ami-23ebb513',
     InstanceType: 't1.micro',
     MinCount:1, MaxCount: 1

};

ec2.runInstances(params, function(err, data) {
})

This code is good to start with launch instances. But i am trying to customize the instance's security group, public key for ssh etc. How can we configure these params? I see not much docs is available that lists out the params supported by aws-sdk.