It seems that Family Sharing is fully released now. And it appears that you actually have to log into a computer, authorize that computer, then log out and have the other accounts log into the authorized computer. You cannot do it completely remotely without giving someone your login details.
I did this with my wife's laptop and our spare laptop. Honestly at least its a start. She doesn't have to kick me off Steam every time she wants to play GTA, because you know I talk to SO many people on Steam, but that's not the point. Before it was hassle all the time now its just a hassle once then after the initial setting its good to go.
I asked on the Steam forums for a beta invite and got a random one sent, messed around with it or a week a few quirks to be sure.
First was the logging in authorizing the account then logging out and etc. its a bit annoying. But I understand it because its ment for people close to you.
Another weird thing is if your playing over the network its just a pure remote desktop session. One of our old laptops with a Geforce 120M cant play stuff at high details but my main PC can. So I used the remote play option. You log into your account on both the PC and Laptop and if your on the same network it won't kick you off from the other machine. You click the game you have installed on your PC on the Laptops Steam and click "Stream" it will stream the game to your laptop over your network.
The thing is it actually plays the game on the main PC but takes inputs from the remote host. So essentially no one can do anything on the main PC because the game is running. Also "authorized" accounts cant stream, only install and play your library. I was having issues because the laptops screen is 1366x768 and my monitor is 1920x1080 so the game was too big for the laptops screen. I messed around but just gave up since I havent had much time to game recently (yay college)