Hello Rubix,
You will need, ideally, a second side water cap for the aqaroll, if that is what you mean by basic water container you use at the moment.
Then you will require a side entry Torbeck valve (from B&Q or similar), a length of food grade hose and suitable connectors to connect the hose to the Torbeck valve and the tap.
Cut a hole in the newly acquired container cap to take the Torbeck valve stem and mount so as the valve will be on the inside of the water container when the cap is fitted.
Fit one set of hose connectors to the valve stem and one end of the hose, and the tap connection to the other.
Leave the valve a little loose when fitting the cap on the container so that you make sure it is hanging vertically when the cap is secured, then just tighten to stop it moving.
Connect to the water tap, and fill, it will stop when the float reaches its cut off position, about half an aquaroll.
Drop your pump in the top entry as usual and thats it.
Costs approx Valve about