Download it from the usual place: http://amaterasu.tindabox.net/index.php?page=downloads
All parts of the common route that are reachable on a first playthrough have been translated, so you shouldn't reach any Japanese text until you enter a specific heroine's route (and it will be very obvious when this happens). But keep in mind that the Shizuru and Akane routes themselves are not available on a first playthrough, so most scenes unique to them are unreachable and untranslated (that's why the stats page says I haven't finished 100% of the common route yet).
All of the images with text that appear in the common route and menus have been translated with the exception of the Memory (Friends/Monsters/Quests) section. The handful of submenus built into the exe are also translated.
There are also subtitles for the opening video (later patches will have subs for the other videos too), since this engine seems to auto-detect subtitle files. Depending on your setup, it's possible this auto-detection won't work and you won't see these subs. Tell us whether it works for you, so we can find out if it's a common issue or not.
As with most partial patches, this one ends in a slightly evil place (albeit one of the least evil ones) so be prepared for that if you choose to read it.
When trying to install your copy of Rewrite, be aware that it only works on Japanese computers, so don't be alarmed when the installation finishes and the .exe refuses to run. Our patch will fix that.
There's no walkthrough this time (you won't need one this early anyway), but there will be an extremely thorough one in later patches.
Edit: If, after installing the patch, the SiglusEngine.exe file crashes the moment you try to run it, then replace it with this .exe instead: