Coolant Flush old school?

[RamahX]

Searches on this subject are very futile... either TMI, or not enough...
'94 W124 M103, can I just cut the drivers side rear heater hose and place a bronze T (instead of the dreaded Prestone plastic one in the kit) and attach a water hose and flush my cooling system like we did "back in the day"?

Would I still need to put in a special 'open' thermostat? Or could I do it without. Or just remove it temporarily while flushing?

Plan would be install T, remove engine block plug and run water hose at low pressure until clear...

MB way is to attach special radiator hose sized T at top of radiator with water hose and install special thermostat.

Just trying to keep this simple. I don't need lectures on what antifreeze to use or 'make sure you run heater' etc, I know all that. Just want to know if the old school way would damage something, and the engine block plug is not something I'm used to from my shade tree days working on US cars.