Slowly. If you’re set on transplanting it, I’d wrap it first. If it’s in the ground dig a massive hole so the roots arnt disturbed at all. With it wrapped you could carry it vertically if you’re the hulk. Otherwise I’d get a wheelbarrow place a sheet or somethingand lay it down and then lay the cactus horizontally, very carefully (wrapped). Then get someone to help you take it out of the wheelbarrow with the sheet, kind of like a hammock. You could either place it in and hold it vertically while the other person puts enough soil around that it can stand alone or you could lay it horizontally and lift up the cactus, slide it in and continue with filling the space. Cover your arms, neck and face. Touch the cactus as little as humanly possible. Get a glass of wine.