Flaps2Approach has written about the genuine B737 CDU conversion process using Simstack. This is one way the Airbus MCDU could also potentially be converted; it does pose another challenge for Simulator Solutions as the screen size for an Airbus MCDU is slightly larger than a Boeing CDU.
Our friend James in the UK is also planning to convert an original MCDU using ARINC without any stripping of the internals of the MCDU required.
At the current time the sim continues to use Flight Deck Solutions MCDU — these are reasonable replicates and work well, however nothing still beats the use of real components. The original tactile feel of a Thales or Honeywell MCDU and the even backlighting is difficult to replicate in simulator models.