Where to hook up boost gauge for ROOTS style supercharger

hey i was just thinking, normally, for blow-thru carb or fuel injected centrifugal superchargers (paxton, vortech, etc. etc.) you can just hook your boost gauge to any vacuum line since its all "after" the blower.. but if the carbs sit on top of the blower, can you still attach to the vacuum port at the base of the carb? i would think not since the carb is pulling through the carb, right? wouldn't i have to somehow hook up my boost gauge AFTER the blower?

Thanks.