You can...
Hello!
Yes you can...I`m doing excatly that now,converting my FAA IR SEP into an JAA MEIR....I also had an JAA CPL MEP when leaving the us! Guess your JAA licences are issued in the UK!?You can do the course in all of the JAR approved states, at an jar approved school - and send the necessary papers to the CAA in the UK,and they will issue the licence...
Look in the LASORS for hour requirement i.e.....I believe it was section F under Instrument!?
Happy Flying,
Rune
Sorry - missread your question...Thought you had an JAA CPL ME=) Dont know how it will work out in your case...