Install addon from a zip file. 

Once done, you will find it underneath Toolbar Panel in 3D View.

How to use:

1. Select all objects you want to group for baking
2. Select low poly mesh as Active
3. Click Rename4Baking button in Lazy Rename panel.
4. Lazy Rename will add _low suffix to active object and also will copy it's name and add _high_ suffix to remaining objects.