I am working on a rooted device. I have connected with the adb shell from my pc and I can verify that the other database exists and I can query its tables.
However i
This is because the app needs root, and needs to change the permissions of the database you are trying to access so that you can actually access it. What you will need to do is, as root, change the permissions of the database so that everyone can access it, do what you would like on the database, close the database and change the permissions back.
This does circumvent security of android, so proceed at your own risk. You can find a code sample at:
http://rratmansky.wordpress.com/?p=259&preview=true