Hey Jad,
There are some interesting changes coming in the next release, but I'm not sure this will be one of them.
That being said, did you see peterB's comment? It does exactly what you need it to do all in one hotkey. Sells x amount of your position and resets your stop loss to the remaining amount of shares.
Long:
CXL ALLSYMB;Route=LIMIT;Share=Pos*0.5;Price=Bid-0.05;TIF=DAY+;SELL=Send;ROUTE=STOP;StopType=Market;StopPrice=AvgCost;Share=Pos-share;TIF=DAY+;SELL=SEND
Short:
CXL ALLSYMB;Route=LIMIT;Share=Pos*0.5;Price=Ask+0.05;TIF=DAY+;BUY=Send;ROUTE=STOP;StopType=Market;StopPrice=AvgCost;Share=Pos+share;TIF=DAY+;BUY=SEND