I honestly would like to know this as well. I am going to the fam's for the holidays today and would like to load it up on my laptop, but want to bypass the wait to download it again.
Yes it's possible, but I would recommend against it. The EULA specifically states the beta is only supposed to be installed on 1 machine. Not sure how hard Bliz would enforce this, but keep in mind it is strictly prohibited via EULA
(I made it a point to read it to check this, as I wanted to install it on my laptop to show some friends when I was coming home for Xmas)