Slitherine

Maybe I'm to slow for this, but I can't get to the beta. When the updater comes on, I
can see the select box on the upper right, with "release" selected. but before I can
mouse to the select arrow and change the selection, the update check is complete and
I go straight into the release version. The whole thing takes about a second.

Any suggestions [other than using PEDs]?

Find the .exe named PandoraUpdater and launch it. After checking for updating and applying it it does not launch the game, so you can change to beta.