Easiest way is to.
1. Put it in service mode.
2. Lower the caping station.
3. Pinch off the drainage hose of the caps, you will have to remove the front cover in front of the pump to get to it.
4. fill up the caps.
5. Move the head back in place MAKE SURE IT IS LOCKED IN PLACE BEFORE you up step the capping station and shut off the printer and the hard power of the printer because you don't want it to cycle with the hose clamped off.
Why do you think you need to do a head soak?