There is a waistpack available for my pump and giving set, but my insurance doesn't pay for it, it's really expensive, and above all judging by the pics, it doesn't look like they have adapted the design since the early 90ies.
I decided to look around online and then I came across the CamelBak Flashflo 45 Oz hydration waist pack, the hydration bag can be taken out and since it's used for hydration it already has holes in the bag for tubing to go through.
I received the waistpack today, put my bag and pump in, and for the very first time did not have to do any adaptations - it was ready to go!
Here are a few photos:
I put my pump in the back and my bag into the front pouch.