Phenolic is nothing but cardboard and a resin pressed into a flat piece of stock. You can easily cut the stuff with a wood boring bit called a Forstner bit as long as you are careful. Tightly clamp your spacer between two pieces of fairly hard wood - the top piece being pre-drilled as a jig then drill through the spacer and bottom as one piece. You should use a drill press to minimize any bottom side of the spacer tearout.

Any fairly good hardware store has these bits but cheaper Chinese made ones are found places like here:

http://www.mlcswoodworking.com/order.../forstinx.html

or here
http://www.rockler.com/CategoryView.cfm?Cat_ID=531

or cheapest, here:
http://da.harborfreight.com/cpisearc...tner&Submit=Go