Even if you're friendly with the NCR, as we are, you will not be welcomed here no matter what.

But you most certainly will find a small detachment within the building. When you arrive at El Dorado Power Station with your Override Chip in hand, chances are you won't find any NCR soldiers outside guarding it. Black Rock Cave is near to the south, Black Mountain to the west, and Vault 11 and the El Dorado Dry Lake to the east. El Dorado Power Station is located on the eastern side of the Mojave Wasteland, due west of the Hoover Dam. In your interactions with Yes Man around that time, he should have handed over an Override Chip that he wants planted at a lightly-guarded NCR locale known as El Dorado Power Station. But protecting him, as we did, will take care of the optional task outlined above, getting one-third of this quest of the way right away. There, you'll have the opportunity to save NCR President Kimball from assassination (or let it happen, or do it yourself, if you so desire).

Indeed, we highly recommend that you first complete the tasks outlined in our Walkthrough for the equally-brief quest known as You'll Know It When It Happens. As usual, how we're going to go about completing this extremely brief, simple mission is completely in line with how our walkthrough has been written so far.