No la, the copper door method seems to be originated from 万奴王. He is the one that migrated to the 长白山 with his tribe. Not the 西王母.
"传说每一代万奴王都是从青铜门后出来的,而且都不是人,是怪物." Another mystery as to what's behind the copper door and how come 小哥 can still remain "human".
西王母's method is the meteor one. I remember in the novel, at 西王母宮殿; there's a corpse in front of the meteor. Then they encounter 陳文錦 there who then disappear into one of the tunnel in the 天石. I remember if 陳文錦 never stay close to the 天石, she would become a 禁婆 like 霍玲. Then before the main character left the place, they saw a person that looked like the corpse staring at them from the entrance of the 天石's tunnel. And that person is implied to be 西王母 (longest living character so far)?! But she also went back into the meteor and the main character can't find her or 陳文錦 again.
But given the novel tendency of "unreliable narratives", I can't be sure that it was 陳文錦 or 西王母 they saw. As you remember, they can wear human skin mask and pretend to be someone else sia. It can be 陳文錦 pretending to be the corpse in front of the meteor. Or even someone else pretending to be 陳文錦 all together.
Plus I don't think the novel has given hint as to what 陳文錦 and 吳三省 were up to 17 years ago. And how come only 吳三省 is still around. while the rest all kichia or disappeared.