Yes, you need to download development build.

You can already do that though. Just download the new DOSBox version, install it then copy all the files inside DOSBox's installation folder into the DOSBox folder located in each DOS game's directory.

I tend to dislike having several versions of DOSBox installed though so I set mine up so updating it is easy:

I have a folder called DOS in that folder I have a folder called cfg with all the config's in. A folder called games with all the game files in and DOSBox is just kept in the main DOS folder so I just have to install it then replace DOSBox the once rather than several times. Then I just uninstall DOSBox (as I don't have it or the games installed per say.)

I also use DOSBox SVN under a separate glide folder for all the glide games such as Tomb Raider.

I didn't say it was a particularly hard hack, and realistically, it's unlikely that a newer version will mess up any games. I think the most common reason for wanting to do this is just to consolidate. Although, some of the newer versions can bring nicer features.