CFA is not really useful for financial engineering, where the most important will be mathematical finance, C++ or VBA or C#, and knowledge of financial derivatives. However, CFA can be a asset and it may provide you some financial sense.
I am also on my way to pursue both CFA and career in quant trading. How helpful? Tough question! The only thing I know is keeping on pushing and everything will work out at the end, if you try really really hard.