I didn't know it at the time (six years ago), but there was a much easier way to reseal my power steering pump. The front of the pump will come off just by removing the six 13mm bolts on the front. That way, you can access the pump radial seal (the most likely to leak) without taking the whole pump or bracket off.
If you have a tandem pump (self leveling system), you have to take the whole pump off to seal it, but you can still take the whole pump off without removing the bracket by removing the two Allen bolts on the back of the bracket and two 13mm bolts on the front. Here is an excellent writeup by Gerry VZ on removing the tandem pump, which applies equally to the non-tandem pump on the 400E/E420.
Power Steering Pump Leak Investigation
If you really need to remove the bracket, it makes it much easier to get to that 13mm bolt on the back if you take the front exhaust manifold elbow off. I think it is held on with 10mm bolts and they can be accessed from the top of the engine compartment. Although you can't see the manifold bolts from there, you can feel for them and remove with a 1/4" drive ratchet. I reused the paper thin metal gasket that goes on the manifold elbow and had no problem with exhaust leaks.