Use this URL to install the package into any organization:

https://login.salesforce.com/packaging/installPackage.apexp?p0=04t4w000000p6Vd

Note: If you are installing into a sandbox organization you must replace the initial portion of the URL with http://test.salesforce.com

Use of clearMDM is subject to our terms and conditions.

When scheduling a Matching or Synchronisation Job, a Blocking Key can be selected (when more than one exists) to use in the MDM Operation. There is also the option to select ‘All’, which will validate against all 3 Blocking Keys, and continue to do so until all 3 have been checked.

The following blog post provides further detailed information.

When creating a Blocking Key Process Request, there is the option to select ‘Is Multiple Blocking Keys?’ and the ‘Blocking Key Sequence’, e.g. 1, 2 or 3. If This field is selected and the Blocking Key Sequence of 2 is entered, the Blocking Key Process Request will start looking for Matches on Blocking Key 2, then 3 then 1.

The following blog post provides further detailed information.