I realize David has probably already solved his issue, but I messed around with my Bosch washer and seemed to have figured it out. It is really not too hard. This is to fix a leak that occurs if you run the washer at all. We had a visible 2-3 inch gash or tear in the gasket/boot. there are many other things that can cause leaks so don't assume this is the probably just because you have a leak. Also, be sure to note that the holes in the middle bottom are supposed to be there.
I ordered the part, but have not actually installed it. I did successfully take the old one out and put it back in place to be sure I did not need to call for professional help. It took me less than an hour first time through when i was figuring all this out. i think it will take me about 10-15 minutes at the most when the new one arrives.
When you open the washer door, take note of the three or four little holes in the middle bottom of the opening. I assume it is important to be sure to put the holes on the new part in the same place.
If you look on the outside of the gasket/boot, there is a wire that wraps around and holds it in place. There is a small spring that connects the wire (this was closest to the door hinges when i did mine - not sure if that was intentional or just where it happened to be). I took a flat head screwdriver and pried it out/off at the spring. The wire and spring came right out. Before you remove the gasket/boot from the outer edge of the door opening, take note of where the gasket/boot is seated around the metal lip in the door opening. This will be important to get it back the same way when you reinstall.
Once you do that, you can push that part of the gasket/boot in toward the washer and you will see a spring that goes all the way around the outside of where the gasket/boot attaches to the tumbler/drum casing. You might be able to use the flathead screwdriver again, but I just pulled on the gasket/boot and it came out. I had to pull pretty firmly, but it came on out. Once that was off, the whole gasket/boot came out.
As I mentioned, I don't have the new part yet (ordered today). However, I put the old one back on to see if I could get it on there. I am pretty sure I did it correctly, but will not know for sure until I get to install the new one. This process is basically the reverse of how it comes off.
I first seated the gasket/boot around the frame that holds the tumbler. Note that you are not attaching anything to the silver drum/tumbler that actually turns. You are attaching it to the frame just out from that. you have to sort of wedge the gasket/boot around a lip on the frame. It should feel fairly secure once it is seated properly.
Next, you need to put the spring back around that part. I struggled for a little while and then figure out something that helped a lot. I pushed the gasket in toward the washer. Once all of the gasket was inside (and that part might have been easier with 3 or 4 hands), it stayed in place and I was able to see what I was doing much better - did not have to fight with the gasket as much.
To seat the spring, I needed an extra hand. The spring has hooks in order to connect it into a circle. I put the part where it hooks together in first. I had my wife hold it down with one hand while I used both hands to work the spring around the lip and back into place. If you are by yourself, maybe some sort of clamp would hold it in place. I tried one of those clips for chip bags, but that would not hold it. She did not have to apply much pressure or anything - just a little to keep it from coming out. The biggest risk was when I released tension on the spring, it tried to pinch her a little. If you keep stretching it around, this will not happen.
Next, I turned the gasket/boot back right side out and connected the outer gasket/boot edge over the lip of the door opening. You have to work all the way around the outside edge in order to be sure it is properly seated.
Finally, you put the wire with the small spring around the outside. I put the wire as far around as i could. Then, I used the screwdriver to pull down on the wire were it connects to the spring with one hand while I pushed the wire into place with the other.
When I was done, it looked like it did before I took it off so I assume it is correct. I will be installing the new one next week and will post how that goes and if it fixed my problem.