Forget it Terry,
If the harsh sun of Vegas doesn't kill your dogwood, the dry soil will. Maybe if you planted it on the north side of a building, and maybe if there was a leaky faucet right next to it, maybe it wouldn't die, but I'm afraid this an example of wrong plant, wrong place. Just because the temperature of the Deep South is comparable to Las Vegas don't think that you can make up for the rest of the climate differences.
How about a nice mulberry tree instead? When I lived in Vegas, I had a mulberry that wouldn't die. It was old
enough to have a tap
root that made it down to the
water table, and it was going to keep coming back, no matter how much it was hacked at. Dogwoods have shallow
roots, and even in the few places in the Vegas Valley where the water table makes it to the surface, I have a feeling the low, low humidity would still burn it up.