I cannot confirm this works but I am reasonably confident.

1. Friend has beta access
2. Log into friend's account
3. Download friends HoTS client
4. Log out
5. Log in to your account
6. Profit

I believe this worked for a friend of mine. Wanted to get it out there for you guys to test.

Tried on EU. Not working.

I've tried it on EU too, can confirm that it doesn't work.