Ok, I'm back on my feet with this project. I finally had a weekend and a couple of evenings to get some work done on this!
So here's where we stand...I tore up the old liner, curb and preslope (preslope was made of wrong material as you recall). I reconstructed the curb and used sand-mix to create the new preslope. (For those wondering, yes, it was the Quikrete stuff

- actually it worked fairly well...MUCH better than what I was using before)
The liner was installed and this time I used silicone as a sealant for the drain. Next, I hung the cement board leaving some space at the bottom, as your tutorial suggested.
I now have the metal lath positioned over the curb (stapled only on the outside bottom) and I'm awaiting the next layer of deck mud (the final layer).
The good thing is that I feel a lot more confident about this setup than I did the previous one.
Unfortunately, the next step will probably have to wait until this weekend, unless I can free up some more time before then.
I just wanted to update everyone who's been helping me out on this one. So far so good (unless you can spot anything I missed...). The picture does it no justice!
Best,
aksival