Aside from removing the vent adjuster thingy, it shouldn't be too much work. You might need to use a dremel to widen the hole if it's not big enough. IMO, it's better to get a gauge pod for your A pillar or one that goes on your dash because running the wiring the way you'd have to with the A/C vents will be a bitch. I think Isaac's car has at least one gauge in an A/C vent...there's pictures somewhere in the gallery. Good luck though!