...according to Richard Lewis... who denies peripheral cheats exist in pro csgo and won't admit players should not be allowed to use their own peripherals.

When release does happen, the timing of which you can get an idea of at SteamDB[steamdb.info], you can access the beta participation menu by choosing the cog in your Steam library CSGO page. This will open a dropdown menu. Select properties. In the window that opens, select "BETAS" from the sidebar on the left.

Assuming this is how it will work, this is how you will then download the beta files in order to play the new version of the game. There will be an official announcement from Valve in some form soon.