Do you mean using the un-dry mixture to spread over stencils, or drying the lace and stenciling over the lace (i.e., using the lace as a stencil)? I'm assuming the former, and though I have never done it, I think it could work provided the mixture is thick enough not to ooze under the stencil, or to spread when you remove the stencil. These mixtures tend to be very loose if mixed per packaging instructions, so you might have to mix it thicker than usual.
You could also spread gray (for silver) or gold royal icing through the stencils; let the icing dry; and then paint it with a small brush and a mixture of silver (or gold) luster dust and alcohol, or a pre-mixed metallic edible paint (I think Rainbow Dust has some).
P.S. Have you tasted the Claire Bowman metallics? They are really horrible tasting, in my opinion, which should probably be another consideration.