There isn't a way built into the existing Cloud Save extension. But, if you're willing to modify the existing extension, you can pretty easily modify the folder that Cloud Save will save to.
0. Install Cloud Save extension.
I'm going to assume you already have the extension installed. But just in case.
1. Make a Copy of the Cloud Save extension.
- Go to the Extensions page ( chrome://settings/extensionSettings ).
- Enable Developer Mode (check box up top).
- Make note of the ID of the Cloud Save extension.
- Make a copy of the extension directory some place, like your desktop. The extension directory will have the same name as the extension ID, something like "dlbemabjbfhjcccahjioenmkgimjbbkd".
- To locate the extensions directory, see this article on extension locations http://stackoverflow.com/questions/2250163/how-do-directly-modify-a-google-chrome-extension-file-crx It'll be different based on your OS.
2. Modify the Cloud Save Extension
- Using your temp copy of Cloud Save...
- Navigate into {temp directory}/{version number}/hosts/dropbox/
- Open the dropbox.js file with your favorite text editor.
- Find the line containing var folder = ''
- Change the location. For example, if you had a folder within your Dropbox folder called CloudSave, you could change the line to read var folder = 'CloudSave'.
- Save the file.
- Go back into the Chrome Extensions page, with Developer Mode still activated.
- Press the Load unpacked extension button.
- Locate and open your working copy of the extension.
- This should take the place of the old installed Cloud Save and now save to your desired location.
Note: I had trouble using folder names with spaces in them. Just something to keep in mind.
Hope that helps!