user points shared multi-site

Wondering if anyone has gotten this to work:
I have set up shared user accounts across multiple sites and would like to be able to view / have points added through any of those sites.

Shared accounts were set up by having all subdomains use the user tables in the main site through settings.php like so:

$db_prefix = array(
"default" => "slave1_", // the prefix for tables that are not shared.
"users" => "master_",
"sessions" => "master_",
"authmap" => "master_",
"profile_fields" => "master_",
"profile_values" => "master_",
);