First, this procedure is quite specific to the mix of code running on openacs.org. It might give some hints into what might need to be done on a site running custom code.
Log onto current openacs server.

psql -f openacs.org-2003-08-30-fixed-2.dump openacs.org
psql -f /web/openacs.org/packages/acs-kernel/sql/postgresql/postgresql.sql openacs.org
psql -f upgrade-4.2-4.5.sql openacs.org


log on to temp openacs server.

start aolserver
visit temp-server/acs-admin/apm/

install packages
Upgrade acs-kernel - no sql scripts
restart aolserver

visit APM
Install Packages
acs-tcl
acs-admin
acs-bootstrap-installer
acs-templating
acs-service-contract
 apply upgrade-4.5.1-4.6.sql upgrade script
acs-subsite -don't run upgrade script
acs-utilities

-restart
visit apm
upgrade acs-content-repository
apply upgrade-4.5-4.6.sql openacs.org
      upgrade-4.6.2-4.6.3.sql openacs.org
      upgrade-4.6.3-4.6.4.sql openacs.org
      upgrade-4.6.4-4.6.5.sql opeancs.org

upgrade search -don't run sql scripts

upgrade notifications
apply upgrade-0.2d-0.3d.sql openacs.org
      SKIP! psql -f upgrade-0.3d-0.4d.sql openacs.org creates indexes that already exist
      upgrade-0.4d-4.6.1.sql openacs.org
      upgrade-4.6.1-4.6.2.sql openacs.org

-restart aolserver

Install packages
Upgrade 
acs-api-browser
acs-content
acs-core-docs
acs-datetime
acs-events
  upgrade-0.1d-0.2d.sql

acs-mail
apply upgrade-4.5-4.6.sql openacs.org
      upgrade-4.6-4.6.1.sql openacs.org
      upgrade-4.6.1-4.6.2.sql openacs.org

acs-messaging
apply upgrade-4.6.2-4.6.3.sql openacs.org

acs-workflow
apply upgrade-4.6-4.6.1.sql openacs.org

bookmarks
apply upgrade-4.1.1b-4.6.sql openacs.org

faq
apply upgrade-4.0-4.6.sql openacs.org

file-storage
apply upgrade-4.6.1-4.6.2.sql openacs.org

--go get irc-logger!!

news
apply upgrade-4.1.0b-4.6.sql openacs.org modified to fix timestamp issue

page
rss-support
skin
static-pages
apply upgrade-4.2a-4.3.sql

wp

-restart aolserver

install workflow package

-restart aolserver

(make sure workflow is enabled before trying to upgrade bugtracker!!!
upgrade bugtracker
apply upgrade-0.9d1-1.2d2.sql
      upgrade-1.2d5-1.2d6.sql
      upgrade-1.2d6-1.2d7.sql
      upgrade-1.2d8-1.2d9.sql
      upgrade-1.2d9-1.2d10.sql

ETP
apply upgrade-1.2-1.3.sql
	

Don't forget to vacuum

Further work

Now that the site is working on 4.6.3 we can upgrade to openacs 5.0.

In a checkout of openacs-org branch do
cvs update -r  

and resovle any conflicts.

Follow the 4.6.3 to 5.0 upgrade procedure: http://openacs.org/projects/openacs/5.0/upgrade-463-50.

After this the only trick will be compiling OpenFTS 0.3.2 and fixing the search system. 

Vaugue guide to this:

visit openfts-driver/ and try to remove the openfts tables from there. Then remove the openfts-driver package from the apm.

After that go into psql and make sure there aren't any index* tables. If there are, drop them. Make sure txt table is also dropped.

Compile tsearch and Openfts 0.3.2 and install them into the database. 

reinstall openfts driver package. Initialize it by browsing to openfts-driver.

If it worked you will need to reindex all the content which includes forums_messages and etp_page_revisions. Only index the parent of a thread, the service contract will index all the children for you. Only index live revisions of content repository items.