Errrr....Are you serious?
Those 3 bolts in the center only hold the rear engine mount.
The X-member is held by 4 bolts up into the chassis (2 on each side)Jack the car safely with jack stands etc, and undo them just enough to create clearance to remove the alternator.
The X-member wouldn't need to come out completely for that job, but you would need to support it with something like a trolly jack if the 4 holding bolts were actually taken right out, because if the exhaust pipe were removed as well as the 3 rear engine mount bolts the X-member would fall right down if not supported.