if python2.5 is used as the default python during installation (by which i mean emerging ardour 2.5), the installation will fail.
Steps to Reproduce:
1.Have python2.5 as your system python
A lot of ACCESS DENIED messages and no installation.
If python is rolled back to 2.4.*, then it will install just fine.
I did this by adjusting the symlinks in /usr/bin to point to python 2.4 instead of 2.5 and it worked.
Did you miss to run python-updater, as you were instructed by the post-install information, when switching from Python 2.4 to 2.5?
Also: If you encouter error messages, please post them. Your description is pretty vague and therefore not useful as a base to track down issues.