I also had this conception that if you sat your IR in a twin you would get the MEP as well but luckly the discussion started at aviation house while sitting the exams so i just went to ask. You definately need to get it before the IR but it is possible to sit it as part of your CPL test.
It also caused me to alter my plans somewhat so Nicky at Naples is going to have the pleasure of my company for 3 days next time i am over hour building.
Hope this helps
MJ