That's just awesome
... now that's what one calls IRONY! Wish I saw this yesterday, would have made an extremely strenuous day bearable!
Edit: BTW, does your friend not want OpenDCL due to having to install the runtime? Would he be willing to accept ARXs in your addon? It is possible to package OpenDCL together with your own code - you need not "install" it per se. There are some samples of loading the correct ARX for the acad version through lisp - just need to make sure you include the licensing stuff. I know the old CDGPurge used to do it this way - you didn't need to install OpenDCL/ObjectDCL seperately - it was included in the CDG package.
The reason I'm adding this, is there's quite a change in the actions between Open/ObjectDCL and DCL. The previous 2 uses a defun declared as a command/arx-callable-defun for each action (or rather event), while DCL adds actions as strings to be read & evaluated as lisp statements. It might mean much more than a conversion, possibly a total re-write.