The best and only way I have and will ever add kalk into my tank is through a drip. It's very simple to do and with a 5 gallon bucket you won't have to worry about it for weeks.
Leave the ATO separate.
The reason KALK cannot be dosed like Calcium solutions is because it also raises Alkalinity.
I am a firm believer in keeping everything separate. If one thing fails the system is not being overloaded with multiple variables.
For instance ATO stuck on or off, you can deal with salinity issues.
If you add the kalk to that you have to deal with salinity and high levels of calcium and alkalinity.
I would also purchase a pH lowering solution that turns Alkalinity into CO2 for when mistakes are made. I think Seachem makes a product that you add directly into the tank to accomplish this. It is a dry product so it has a nice shelf life. However, when your first starting off and trying to determine the drip rate it is good for if you make a mistake here or there.