Are you talking about converting your FAA ratings to JAA? If so it takes about a year, about 15k and actual flights that you might have to do overseas for the instrument rating depending on your experience. I looked into it but gave up on it, too much for me plus you need to have dual citizenship or right to work for many JAA airlines. Also many FO positions are fine if you only have a CPL but you need the ATPL written.... from the JAA or local gov authority not the FAA one.