hey padme.....  had  metastock fx  when it first came out but back then forex did not interest me....  so i did not look at it very close..... from what i remember qc was the only data vendor and it did not interface with any sort of broker, of course  that may have changed....   orders would have to be input manually ..... 

you might be able to use a third party apt to auto trade  signals derived from metafx.....

unless i'm mistaken,  we should be able to code trailing stops using psar and moving averages in mq4.....h