You need to either install from the unstable repository, or build from source.
The former is easier, in that it installs just like any other package. The downside is that it'll update every time a new change is made to the code, and that may break sometimes (as well as there being an update every few days, at least).
The latter is a little more complex, especially if you're not used to compiling code. The positive here, though, is that you can build a version that works for you and then stay with it.