pass aditional paramter before social login

This is covered in the next version.
There you can add this kind of hook:

function oa_social_login_set_new_user_role ($user_role)
{
	//This the the default behavior, usually the default role is subscriber
	$user_role = get_option('default_role');

	//This is an example for a custom setting with two roles
	$user_role = 'author editor';

	//The new user will be assigned this role
	return $user_role;
}
add_filter('oa_social_login_filter_new_user_role', 'oa_social_login_set_new_user_role');

We are still testing it, but you can download it here to give it a try:

https://secure.oneallcdn.com/extensions/wordpress/beta/wordpress-3.x.x—oneall_social_login-4.6.zip