How can I access objects in the Desktop Table (ROT) from Internet Explorer Protected Mode?

I've tried the following:

• Setting HKLM\Software\Classes\AppID\{AppID}\ROTFlags
  
  to 0x1
  
  (as recommended here )
• Registering an object to the ROT with the flag set ROTFLAGS_ALLOWANYCLIENT
  
  .

However, I always get the error 0x800401e3 (Operation unavailable)

whenever I try to access the ROT object from IE protected mode.