I made a video for it..
i find this to be the best way to get killed 100 times by the Alien..
Once i completed the game ( for the One Shot Walkthrough on hard ) i load up Mission 17.
Walk to the save to the right and throw a pipe bomb to kill the shotgun guy and immediately throw a Noice Maker and save.
You must be quick because the Alien comes really fast.
So if you die ,load the last save and the noisemaker is still going off so the Alien comes really fast.
This is on Hard mode so the alien comes faster on Hard of Nightmare.
I got this trophy in no time.
Around 35 minutes i think .
I got it Platinum now.
Such a great game..
Good Luck!