Hello, again.
Unfortunately, I don't think you'll be able to do this.
The way that Google now has their services integrated, it seems to be
that one identity is irrevokably linked to all of them.
Gmail Identity = Google Account Identity = Orkut Identity, etc.
I don't see a way to alter this. You can create an Orkut account
with the other Google account, but I don't think you can transfer the existing one.