Warning, don't use CA glue with the fiber as it will melt. I find that sanding the top of the LED flat helps, just don't sand it so far that the cathode inside the lens is exposed. I agree about the polishing too.
It's also possible to drill a hole in the tip of an LED the size needed to fit the fiber optic strand into it, glue the fiber into the hole, and then cover the LED with heat shrink tubing.
If your going to use fiberoptics I don't really see a need to use Micro or SMD LEDs. A 3mm or 5mm will work well unless you are extremely tight on space. However, whatever LED size you choose to use they will all function the same. Just point the LED directly into one end of the fiberoptic, and get light out the other end. Avoid sharp bends in the optic strand or you will loose light. It helps to sand the ends of the optic strand with a very fine grit sandpaper to 'polish' them and increase light output. Alternatively you could melt the end of the strand with a heat source (lighter, soldering iron, etc) but use caution as the optic strand will mushroom and deform rather quickly. Use heatshrink tubing or a small piece of metal/plastic tubing to couple the LED with the fiber strand(s). Pick a tube that fits snugly around the LED for best performance. As always, use a resistor with your LEDs (reguardless of the type you choose) to reduce the current or you will blow them instantly.
Ulrich models does a kit for the SD70 ace.
http://www.ulrichmodels.biz/servlet/the-615/Athearn-SD70ACe-LED-Lighting/Detail
take a look because it may give you some pointers. I did the ditch lights using the very small LED'a and it worked very well.
BTW, I think you mean Micro LED rather than Macro?
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum