Not sure if you could tell xPlore not to index objects generated from a specific source.
I would do it this way
1. Create a sub try of the object type that you are creating objects of.
2. Install xPlore filters
3. Configure filters to not to index the nes sub object type.
The subtype would not have any attributes of it's own but inherit all from the super type. It would act as a classification placeholder for xPlore
Hope this helps you.