Messless coolant draining?

[DieselHead]

I've never had to do a coolant flush before on my 300D but I think it desperately needs to be done soon. I located the engine block drainage point and the drain cock on the bottom of the radiator. My question is, how would one go about opening up the bolt on the engine block and have the coolant come out in a controlled manner into a container? It seems to me that once that bolt is undone, it'll just come streaming out all over the place. Thanks for the advice.

Alex