I had a pair of Xears iems that I needed to take apart to replace the cable inside the housing (it went bad). To get into the housing, I used a straight razor blade and just kept working it into the seam of the housing until it came apart.
To glue the housing back together, I used this product and it worked great.
Loctite super glue w/easy brush applicator: http://www.amazon.com/gp/product/B0007894AW
I just used the brush and applied a little bit of super glue to the seam of the housing, pressed the two pieces back together, held it there for about 30 seconds and then let it set for about 10 minutes (extremely easy). The housing has held together perfectly fine ever since, with no problems. I'm not sure how easy it would be to open the housing back up if I needed to (to break the super glue bond), I haven't tried. I would definitely recommend using super glue that has a brush applicator though. I was able to apply the right amount of glue very precisely, because of the brush. hope that helps