[EE] Creating gerbers for blind vias in Eagle.

[Neil]

Anyone know how to generate gerbers for blind vias? I can route the
board with drills going only through certain layers, but then there are
2 things I'm not sure how to do:
(1) How do I generate a drill file for each sub-board? I expect I'll
need to give it a file with drill holes for each sub board, but how
would the drillcfg.ulp file know which layers the drills go through?
AFAICT, that ulp does not check for layers.

(2) How do I tell the CAM processor which vias only need to be on
certain layers?

FWIW, I'm using Eagle 4.16r2, and the tutorial does not indicate how to
do this.

Thanks,
-Neil.