Upgrade Revolution from GIT
For this to work you will need a terminal connection to your server and the possibility to run terminal commands on your machine. If you have GIT installed on the server you'll probably want to skip step 3 and 4 or use some other GIT command or GIT tool.
Make sure you first BACKUP(files and database) your old install just in case something goes wrong.
1. Get a local copy
git clone http://github.com/modxcms/revolution.git
2. Clean the local copy
Remove git files. I'm sure there's a better way
rm -rf `find revolution/. -type f -name .gitignore` rm -rf `find revolution/. -type d -name .git`
3. Archive the copy
zip -r revolution.zip revolution/
4. Upload the archive
scp revolution.zip username@host:public_html/revolution.zip
Or use your preferred FTP program.
5. Unzip on the server
6. Copy files if needed
Overwrite the files. Your paths might be different
cp -r revolution/* ./
7. Configure build.config.php
Create and edit the _build/build.config.php file from build.config.sample.php
Navigate to YOUR_SITE.COM/build/transport.core.php
Navigate to YOUR_SITE.COM/setup
Official MODx documentation can be found here.
Please share your upgrade process in the comments section. I'm sure there is room for improvement as my "terminal" and GIT knowledge is limited.