I've munched through this thread.

DIY: ZF 5HP19 Reverse Drum Fix - E46Fanatics

It looks as though he removes the valve body first. However I'm now a little confused to which seal I have and which is number 10 in the realoem.

I've drawn two black lines, now correct me if I'm wrong but I believe there are seals located in those locations.



Assuming that number 10 on realoem is very outside seal, then the reverse drum guy on e46fanatics, merely undoes the bolts and pulls out the assembly, and you can see the seal in the picture.



Now if the seal that is number 10 on realoem the inner one on the bronze pump, then I appear to be a little more screwed.