What I do know is how to access EJBs from RAP.So maybe a workaround solution could be to delegate MC bean's logics on to an EJB class, and using that EJB class from RAP.
The draw-back here is the need to refactor/change existing classes in BU layer just because of RAP UI layer...
Afaik, you can inject MC stuff into EJBs.
So you could simply inject MC's Kernel or Controller into EJB and go from there.
If you would to abstract the MC lookup logic, behind some interface:
* from ServletContext
* from EJB
then you probably wouldn't have a hard time changing this.