So, where are you at? The script is running, and the clients have the data in their local WMI namespace, root\cimv2\sms_sharepermissions ?
So all that's left is to modify hardware inventory to pull that custom WMI Namespace in? If so, it's not too horrid. Take note of a workstation (or server) to which you have remote rights to; and which has run the script, so that on THAT specific
machine, root\cimv2\SMS_SharePermissions exists.
In your CM12 Console, Administration, Client Settings. Right-click "Default Client Settings", Properties. On the left, select "hardware inventory". then on the right, Set classes..., now the fun part.
Add...
Connect..., and put in ThatServerOrWorkstation (for computername), and wmi namespace is root\cimv2. Click the option "recursive", Connect. (the trick here is rights to the target).
From the results, it might be easiest to click on "classname" at the top for sorting, then go find SMS_SharePermissions. Select that, ok ok ok ok (however many times you need to agree); and... we're done here. Sit and wait for inventory to report
that data up. If you're paranoid, you can monitor dataldr.log; and force policy refreshes and hinv deltas on some boxes; but the key is patience. if you think you've waited long enough; you probably haven't. ;)