Best method...d not do it. Worried about sludge, run good quality oil with a high detergent quality (honestly, any major brand oil these days) and change at short intervals. Two reasons:

Where is that sludge going to go before it become liquid again? Likely the pump pick-up screen. This can easily lead to oil starvation and premature engine rebuild.

What do you think is keeping that engine from leaking out all the seals until you have spent some time making sure the pcv system work and works well. This include cleaning the flame trap and replacing all the vac lines that are dry rotted.

There so, so many better places to spend your time and money. If you absolutely, positively feel you have to do this, just add a /2 quart o ATf at the oil change and let the engine gett up to operating them for about 15 minutes. Then change the oil and filter.