The M3W uses a concentric throw-out bearing. I believe it is Mazda transmission, either out of a late model truck or one of their small sports cars. Ford (for obvious reasons uses the same design. The bleeder is on the top just under the oil tank. There is a black plastic bleeder that looks like a brake bleeder. If you the clutch is slipping you either have a burnt disk or the concentric throw out bearing is binding/blown. Could also be a binding clutch master cylinder behind the pedal, but that is rare.
I'd suggest looking at service bulletins for Mazda concentric slave cylinders.
I'd also remove the plate above the pedal cluster and watch the cylinder while someone else pushes the clutch. Look for abnormalities.
As far as removal, I've seen exploded diagrams of the car and it seems like servicing the clutch is similar to any other car. You likely have to remove the bolts between the drive adapter assembly and transmission, wrap some lift belts around the motor, and pull it forward.
