How can I create a threshold processing rule for the logical disk object to specify free disk space (NETIQKB1522)

goal
How can I create a threshold processing rule for the logical disk object to specify free disk space in megabytes instead of percentage?

note

Example steps for Security Manager 5.1/5.5:

How do I set up a performance processing rule to look for free space on HD's?.

1.  Create a new provider with the following properties:
        Windows NT Performance Counter
        LogicalDisk-Free Megabytes (Pick Drives and sample time)
        No Synchronization is needed.
2.  In your custom rule group area create a new Performance Processing Rule
        Pick Compare Performance Data (Threshold)
        In provider type, pick the new provider that you created in step 1.
        Take the defaults until you reach the threshold page.
        Set the threshold in MB.
        Select Generate alert and setup the alert Severity you want.
        Follow the remaining prompts to the finish.

Windows disk performance counters must be started.  (See diskperf /? for more info)

Formerly known as NETIQKB1522