AutoCAD 2010 :: Block Control In Reference Drawing?

I'm using Architecture 2011, but the problem is pretty generic.

I am working with a very complex vendor drawing and using it as an xref to my working drawing.  I need to be able to freeze parts of the xref and change colors (for plotting purposes) of other parts. Under ideal circumstance this would require simple layer manipulation.

My problem is that a large percentage of the vendor drawing is made up of blocks.  There are nearly 1000 different blocks.  Most of these blocks were created using layers other than 0 - quite often more than one layer is used.  Sometimes the block is inserted on a layer that was used in it's creation, sometimes not.  The only way I can omit one of these blocks from my drawing is to figure out what layer was used in it's creation and freeze that layer.  You can see how this could be a pretty tedious process.

My limited CAD knowledge only gives me: edit all 1000 blocks, changing them to layer 0