I am trying to do the same thing. This is what I figured out sofar.
Put "PostgreSQLDatabase.php" file into "SilverStripe\sapphire\core\model". This is where "MySQLDatabase.php" is.
Second, you have to replace the file "config-form.html" in "SilverStripe\" with "http://open.silverstripe.com/raw-attachment/ticket/3362/config-form-pg.html"
Last, "install.php" has to be replaced as well but I cannot find a replacement file for PostgreSQL. I guess we have to wait a developer to write it cause I do not know any SQL stuff.
I hope this shed some light.
Hey Geoff, I was under the impression that the postgres version was not yet fully funcitonal. At least in my experience, I was unable to add new page types reliably - they simple didn't seem to get built.
Should we be adding tickets if we find bugs in the postgres module?
As far as I know the installer has not yet been updated to support multiple databases (postgres and mssql support are both still alpha code). You would have to bypass the installer.php (by just deleting that file and setting your configuration in your _ss_environment.php file (or if you do not have one your mysite/_config file)