So, you're here either looking to play the game, or play around with the game's code. First of all, you should already have the Windows Shell Extension for Subversion.
http://tortoisesvn.tigris.org/ If you do and you've installed it, skip the next paragraph.
Basically, it's a client that lets you access/upload/download files from the SVN repository. Make sure you pick the right one for your computer (32 bit or 64 bit). In order to set it up, all you have to do is install it, and then when it's done, right click in your windows explorer and there should be a new option to 'SVN checkout.' This is what links that directory you're in to the SVN on Sourceforge, and lets you get all the goodies in one nicely compiled and organized structure. After you do it, it'll download the files from the SVN, and now you can update or commit, which is basically downloading and uploading from it. On to the meat.
1. If looking to edit, you can edit with simple text editors. More likely, you'd have downloaded Lua, and you can use the free editor that comes with it.
http://www.lua.org/2. If looking to play, make sure you've downloaded the TE4 engine.
http://te4.org/3. Now, go to your TE4 engine folder's modules folder, and put the crimelike folder you got from the SVN repository in there. You can just simply checkout the directory in your modules folder as well, but that'll require some wrangling, because of the way it's separated into the trunk and branches. For now, I just dumped the contents of the trunk folder into a crimelike folder in the modules folder.
4. You're done! Play! Code! Sprite! Write!