How do I install Google Chrome beta/dev for all users?

New Info

Well, since the Google Pack is now discontinued, people will need a new way to deploy Chrome for all users on a system. Thankfully, Google Chrome's Alternate Installer allows you to do just that. In fact, if one pays careful attention to the URL parameters, all kinds of interesting options present themselves... One can download any of the Stable, Beta, or Dev channels for one user or all users, online or offline installers. For the OP, this link will download the online installer for the Dev Channel for all users.

Old Info

Another option for getting Chrome available for all users is to install it via the Google Pack -- it uses Google's Updater mechanism rather than the MSI. It may also be required for the following instructions to work, as I'm not sure that the MSI installs Google Updater.

That said, once you have Chrome installed for all users, follow the instructions in Comment #1 on Chromium Bug #33682:

Change the value of the ap string in Google Chrome's subkey under HKEY_LOCAL_MACHINE\SOFTWARE\Google\Update\ClientState or HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Google\Update\ClientState to 1.1-beta or 2.0-dev.

After this is done, the next time Chrome updates, it will update to the selected channel.

Also of note: The bug is marked as WontFix. Google does not plan to allow for deploying the Beta or Dev channels by default.