I believe 2240 is a supported system under CMODE.
You might want to run it through the compatibility matrix to be 100% sure your config is supported:
They system did not nescessarily have to come from the factory pre-loaded with CMODE. I believe brand new systems give you an option upon first boot if they are not pre-configured.
If you have a NOW account, I would launch the My AutoSupport utility and run the Transition Advisor to make sure there are no caveats.
I would also strongly recommend that you read the 8.2 CMODE release notes and documentation:
As you stated, you have no data to migrate and this is a lab environment. If you do not care about any existing data, then wipe the system clean and install in CMODE.
Again..if you have a NOW account and your system is registered, you can download the best version of OnTap that your system supports.