Definitely a home job. you will need to drain the block as well as the radiator, to try to remove as much water as possible, it was easier for us having stripped & rebuilt the engine, but a tiny amount of water shouldn`t have much effect.
You should be able to run it with the radiator cap off to vent any steam from any water that may be left in the system, as the 4Life won`t boil at under 180°c.
Let us know if you think there is any performance benefit!
Cheers, Nik.