An upgrade for Tinyportal is very simple:
1. Upload the new package
2. Uninstall the old one (do NOT delete existing data)
3. Install the new one
An everything is fine...
Updating from RC1 to RC2... not so simple!
You will have copy the whole new source to your forum directories and run upgrade.php
Then you will have to reinstall TinyPortal (your TinyPortal content wil be fine though)