I'm seeing recent posts like this that seem to indicate that I can go as far as create my own transactions (and even gives a webpage where you can feed them back into the system without writing or interfacing with your own client)

I'm guessing that it would be rather difficult to get this to work with coins that you currently use with the official client?  Is there a way to get to the private keys without completely shutting down the client and writing a separate program to open up the keystore?