I don't have the answer to his question. But pardon me for kpoing.
I don't think the TS is asking 'how can MLU prevent vibration'.
MY interpretation is he already knows MLU can prevent vibration. He is asking how to activate that function.
'How to do' & 'How do' mean different thing.
Maybe I am wrong :dunno:
Only TS with interesting user name can answer the question, but I interpret it same as you.
"how
to do mirrow lock up to prevent vibration??"
Sounds like he wants to know how to do it, rather than "how does MLU prevent vibration".
Anyway, since we're on the topic of MLU, it might be worth noting that MLU is most useful at certain shutter speed range. The exact value is subject to much debate, but take it as between 1/30 sec and 1/2 second with a large margin. For faster shutter speed, the movement will be frozen. For slower shutter speed, the amount of time of light entering the shutter is more than the short period of vibration.
Having said that, when tripod mounted, remote released and static scene, there's never an image quality penalty to using MLU.
On my Canon, if I'm too lazy to attach my remote release, I use timer mode with MLU enabled in custom function. That way, I press the shutter release button, mirror goes up, and a few seconds later, shutter curtain opens.