The order functionality in the MT4 interface will allow you to close positions non-FIFO, but the accounting on the back-end will still close the orders according to FIFO.
The same is true with hedging. You can hedge trades on the MT4 interface, but the accounting on the back-end (when you check your statement through www.myfxcm.com) will show the positions having offset each other. This applies to MT4 with FXCM US (FXCM.com).
I also agree with rhodytrader on the general point about trading and the accounting basis of the trades…