Introduction
Papervision3D, or PV3D, is not a software but a series of files of ActionScript class. There is no way to install it for Flash downloading a single file and double-clicking. Plus PV3D is constantly involved and need to be regularly updated. Subversion is a version control system that would enable you to keep one copy of PV3D updated on your computer. Then svnX, SCPlugin or TortoiseSVN for PC would be installed in order to control Subversion easily. Finally you would configure your Flash application.
1. Creating Papervision3D folder
Start by creating a folder "Papervision3D" in your Documents or anywhere, in order to save a copy of the full PV3D project (about 100 Mb).
2. Downloading class files

Mac or PC, you need to install a Client version of Subversion.
It works with a distant Server version of Subversion that shares the PV3D project online.
If your are on a PC, go here :
Subversion + TortoiseSVN
On a Mac, simply download My Subversion-1.4.4 Package and install it.
Then select one of those ways to control Subversion :
- SCPlugin, easier
- svnX
Subversion + SCPlugin [ 2.6 Mb ]

SCPlugin is a plugin that enables you to control Subversion directly in the Finder by right-clicking.
Download SCPlugin here.
The installation requires that you close your session on your Mac.
Once done, just go in the Finder and right-click onto the folder Papervision3D you just created.

Select "Plus > Subversion > checkout".

Indicate the URL "http://papervision3d.googlecode.com/svn/trunk/" in Repository URL...

Then click on checkout.

The downloading process starts and you can check the progress.

Subversion + svnX [ 1.1 Mb ]

This way is a bit harder.
Download svnX here.

Copy svnX.app in your Applications folder and launch it.

Go in the Window menu and click on Repositories.

It contains your list of project you want to download with Subversion.
Select the default item or click on "+" to create a new Repository for PV3D. Type "Papervision3D" in Name and copy "http://papervision3d.googlecode.com/svn/trunk/" in Path, then type Enter.

Double-click on it. Its details appear.

You can see the list of all the updates brought to Papervision3D. Click on svn checkout and find the folder Papervision3D you presently created.

The downloading process starts and the window Working copies appears.

"My Project" would be renamed by "Papervision3D".
Double-click on it in order to check the progress.

There is a button called Update that enables you to keep Papervision3D updated.

Subversion + TortoiseSVN [ 3.2 Mb ]
Download CollabNet Subversion Command Line Client v1.4.6 [ 3.2 Mb ]

You need to register and to confirm your subscription in your box-mail.
Then you can download Subversion.

Install it by double-clicking on the file with the extension "win32".

Follow instructions by cliking on the "Next" button.

Once you installed it, you need to install TortoiseSVN.
Download it here.

Select an Installer to download.

Launch it and follow instructions by cliking on the "Next" button.

Installation need your PC shutdown.

Once your computer restarted, just open the Windows File Explorer.
Double-click on the folder "Papervision3D" you presently created and select "SVN Checkout...".

This window appears :

Indicate the URL "http://papervision3d.googlecode.com/svn/trunk/" in URL of repository.

Then click on "OK". The downloading process starts :

4. Configure Flash CS3
Launch Flash CS3, open the Preferences window (Edit menu for Windows and Flash for Macintosh) and click on ActionScript in the big list.

Click on Parameters of ActionScript 3.0, click on + and then the button symbolized by a target in order to select the folder "Papervision3D/as3/trunk/src/" of your Documents folder. You should have a window that looks like that :

The installation is done! Click on OK and restart Flash CS3 to use Papervision 3D in your animations.