Cant lay my hand on a reference yet, but the multi engine IR must be valid (in date), you must hold an MCC certificate, and have passed the ATPL knowledge subjects. The CPL validity is not your issue here!
Edit: Its under JAR-FCL 1.250 Type Rating, Multi-pilot Conditions.(Pre-requisite conditions for training)
http://www.jaa.nl/publications/jars/607069.pdf