You should have 25 hours of groundschool - about half which refreshes the CRM/HF stuff from your ATPL, looks at teamwork, leadership, decision making and crew co-operation theory and the other half of which covers typical SOPs, use of checklists, standard calls, briefings, monitoring and operation of the simulated aeroplane which will be used for the practical training.
The 20 hours of synthetic training ( 5 x 4 hours usually) should cover: general handling, ILS approaches, non-precision approaches, go-arounds, route flying, engine failures before and after V1 and in flight, single engine approaches, general emergency handling and diversion.
The emphasis of the synthetic phase is NOT on flying (the autopilot should be used as much as possible) but on the crew interaction, decision making, monitoring and challenging, situational awareness etc. Also, it should include liaison with cabin crew, company ops etc.
Throw yourself into it, learn the SOPs, keep an open mind and youŽll gain a great deal from it. Don't be fooled by the fact that there is no test - it requires a good deal of effort and application for you to get a "handle" on multicrew ops in such a short time.