Upgrading from ActiveCollab and keeping the old install

To upgrade from ActiveCollab and keeping the old install, you just have to follow the upgrade.txt instructions with the following amends :
step 3 becomes :
3) Unzip the ProjectPier package to a new directory on your hard drive, then upload to A NEW DIRECTORY on your server.
* do the steps 5 to 6 in the previously created directory
* do the extra steps :
7) copy the files from the /public/files from the old install to the new one, this copy the avatars and company logos
8) copy the files from the /upload from the old install to the new one, this copy the stored files (I do not use the database storage mechanism).

Hope this will help somebody else.