I tried a pull request but due to the missing system description (.1.3.6.1.2.1.1.1.0) and system object ID (.1.3.6.1.2.1.1.2.0) of these IBM TS4300 devices it would slow down all host discoveries so the pull request is about to get rejected/denied (for a good reason)
The only option is to make this an mkp and make it available at exchange.checkmk.com
which I do not have time for.
So if somebody likes to do that, please go ahead.
And if possible kick IBM to provide a system description (.1.3.6.1.2.1.1.1.0) and system object ID (.1.3.6.1.2.1.1.2.0) in future firmwares.