ADMIN EDIT: The factory procedure for VB R&R is at this link, also attached at the bottom of this post.
There has been much discussion on the 500E and second gear starts. While several options exist to achieve permanent and temporary first-gear-starts, I am describing replacing the valve body to achieve permanent first-gear-starts.
I used a valve body from a E420 or 400E obtained by Honcho at a Houston pick-n-pull, pictured below.
First I elevated my car by placing the car on 4 Esco jack stands. This simply cannot be done with the car on the ground. Locate the transmission pan pictured below. I suggest that you cover the floor with cardboard, an old blanket, newspaper, etc as transmission fluid can get messy - particularly when you remove the pan. I used large pieces of cardboard.
NOTE: All of my pictures are taken from the passenger side. The right side of the photos faces the front of the car. (See crossover pipe above for orientation.)
I suggest that you clean the area of any sand or dirt that could make its way into the transmission. Mine was fairly clean, but I wiped it down a bit.
Next drain the fluid. This would be a great time to change the fluid if needed, including the filter and pan gasket. My car's fluid was fresh as I changed it recently. I re-used my fluid.
Locate the drain plug on the transmission pan. You will need a 5 mm hex to loosen the drain plug.
Loosen the plug and drain the fluid. If you are re-using the fluid, make sure you drain it into a hospital-clean container. I used brakleen to clean the 5 gallon bucket that I used.
Allow the fluid to drain for a few minutes until it just drips. I reinstalled the plug loosely and prepared for the removal of the transmission pan. I moved my drain bucket to the side.
In some cases, you will need to remove the crossover exhaust pipe in order to remove the pan. I have plenty of clearance and did not need to remove it.
Next you will need to remove the transmission pan by removing 6 bolts. You will need a 13mm socket for these bolts. Carefully remove the bolts and keep track of where the bolts were located. You will need to put them back in the exact same order. I understand that the bolts are different lengths. I like to remove the bolts in the front of the car, the rear of the car, then remove the middle bolts last as they are easiest to access. [Edit: It is suggested to make a cardboard template of the pan, then stick the bolts in the appropriate spots on the cardboard. I did this. But be careful that you don't get any cardboard fuzz on the bolt that will get into the transmission. (Thanks Ron for the suggestion.)]
Carefully place the unbolted pan on the floor below to catch the drips. It will drip for days - so get ready to get messy.
This is what you will see with the pan removed.
On the left you will see the filter - change it if you are doing that. The valve body is on the right. It is held in with 15 10mm bolts. Notice that the three bolts closest to you are gold in color - this is different than the other 12 which are black. Those 12 are all the same length. Remove the bolts and the valve body will come right out. Be careful - it is heavier than you think.
Put the old valve body in a clean place - but be careful as it is full of fluid.
This is the point where I couldn't take more pictures as my hands were drenched in transmission fluid - so bare with me.
Now you need to install your new valve body. It quite simply bolts back in as easily as the old valve body came out. BUT THERE IS ONE VERY IMPORTANT STEP! You need to make sure the connection is made with a little part on the transmission and the white, plastic part on the edge of the valve body. See it at the top right side on the pic below. (Honcho, can you correctly label these parts?)
Once that is properly aligned, reinstall the 15 bolts. Rember to place the gold colored bolts in the correct place. I tightened these firmly - but did not torque them to a specific value.
Next you will need to carefully re-install the transmission pan. If you are doing the full service, install the new gasket. Loosely tighten all 6 bolts in the appropriate order. ANOTHER IMPORTANT STEP: DO NOT OVERTIGHTEN THESE BOLTS. These bolts should be only be tightened to 8NM. That isn't much! I tighten in a criss-cross pattern and repeat it several times.
Re-installed pan with a nice coating of trans fluid.
Don't forget to tighten that drain plug!
Refill your transmission fluid. I filtered the fluid and added it back to the transmission through the dipstick. Be careful and add the fluid slowly.
Check your work, lower your car, and take it for a drive. I love the first gear start! And it worked perfectly right away. When you return from your drive, check your fluid again and check for leaks underneath.
Well done and enjoy!