This article helped me upgrade my turnkey install, which is what I think your trying to do.
Scoot down to about a third of the way through the article to Danilo Pires submission entitled "The Upgrade (0.8.4 to 0.9.4) process in 17 simple steps"
I noted a few exceptions:
- the
plugins_assets
directory didn't exist, create it in between steps 7 & 8.
- steps 10 and 11 worked better when I added:
--source http://gems.rubyforge.org
to the end of the command.
- before step 12, issue:
rake config/initializers/session_store.rb
Also, steps 10 and 11 can fail with a terribly misinformative error message. Keep trying the command (it does work) until the server decides to give you some sugar. Could be hours though. See here.