Don't be silly.
This won't work for three reasons:
- The amount of water used is becoming very small indeed and most machines will have reached the desired water level before any hot water reaches them.
- European machines and detergents work on the basis of contact time. This is achieved in part by the machine having to heat the water.
- If hot water were added directly to a machine containing items with proteins on them (e.g. anything involving egg), then the proteins will set on the items and be much harder to remove.
The system used in the U.S. assumes hot water (lots of it) and a gritty detergent which shot blasts the best china.