Do you want to help track down bugs and get talents balanced?
Most importantly, do you want 1.3 to come out Sooner™ rather than Later™?
Then read on!
The new Chronomancer classes are mostly finished and ready to go but there are still some balance issues and bugs that need to be sorted out. Right now it would be a huge help if we could get more feedback and have a more cohesive list of what still needs to be done. If you want to help out then here's what you can do:
1) Install git
2) Download the newest development build
3) Bend time for fun and profit
1) Installing git
There are a lot of different git clients out there. I tested a bunch out and hopefully this one should be extremely simple to use for what you need here.
Grab SourceTree here and install it: http://sourcetreeapp.com/ (11MB download)
You might need to register an account once you run it, if so this is free and very quick.
That's it! There's no complicated setup here to mess with really.
2) Downloading the development build
Run SourceTree! At the top left of the program there is a Clone/New button.
EDIT! Everything has been merged into the master branch, so we're finally back to that.
For the Source Path / Url bit, put http://git.net-core.org/tome/t-engine4.git
The destination path can be wherever you want the dev build to go, and by default will probably try to stick it in your documents folder.
...that's pretty much it! It should look something like this:

Now just click Clone and you're on your way! This might take it a bit (~700MB download).
Once it finishes then you're done messing with SourceTree for now.
One last thing to grab and then you're ready to play. Head over to the last page of this thread and download the newest build: Nightly SVN Builds (4.6MB download)
Extract the contents of that zip into wherever you had SourceTree stick the dev build. Now you should be looking at something resembling this:

Look at that shiny new .exe ready to be run!
3) Playtesting
Okay, you probably don't need a guide to play the game. If you don't have the two classes already unlocked you can use this addon for now to just not worry about that: Ignore Race/Class Locks
Now just give it a whirl! Please post all feedback here, and with your help we can hopefully make Later™ a thing of the past.
Edit - These steps are aimed at Windows users, if you have experience with this process for OSX or Linux and want to help out please do
Edit 2 - Updated git address
Edit 3 - Updated git address again to the current test version
Edit 4 - Updated git address! On the master branch we go