There are a few ways of doing this and all basically involve using the reverse proxy or "ProxyPass" feature of Apache to accomplish it.
1.) Create a normal vhost and simply symlink the root directory of the site you want to mirror.
Eg. originalsite.com and newsite.com
You would symlink like this:
ln -s /vhosts/originalsite.com/httpdocs vhosts/originalsite.com/........
There are all kinds of threads and links on the internet, and this seems to be a contentious issue butI don't know why.
95th percentile is either a good deal for some or a big rip off for others, Ijust said it there :)
But the reality is that for MOST people who transfer low amounts of data but burst to higher speeds such as 40mbit+ even for short periods of time, then you'll pay a lot of money to do that.
Basically 95th percentile is an-old archaic method........