I used the "RIFT" choice in the Install Software menu to install from the beta .exe (i.e. I pointed the installer at that .exe, rather than allowing Crossover to automatically download the normal client). It's the Microsoft Visual C++ 2008 package that allows the license agreement to render, but I haven't been able to actually get the installer/downloader going, so agreeing to the license is small comfort.
Anyway, typically we don't spend a whole lot of time on beta clients because that invariably results in a lot of "wild goose chases" with bugs that don't later appear in the final version. It'll still be good to take a look at each subsequent beta and see if the installer mechanism changes enough that we can work with it, but we probably won't be re-assigning any devs to the task of debugging the beta installer for the aforementioned reason.