Well, after spending about 7 hours on my DIY illuminated ZHP knob, I finally got it to my satisfaction. Like with doing any job for the first time, I spent a bit of time figuring out the best methods for doing certain steps.
I took my time removing material from the ZHP knob since I didn't want to accidentally damage it. I wanted to minimize the material removed because I wanted to retain as much of the knob's weight as possible.
It took some time to get the alignment of the shift pattern right and sit flush with the top of the knob. It took me about 6 or 7 tries before I finally got it right.
Knowing what I know now about what was involved on this job, I'd probably just buy that ebay knob for $120 if I were to do this again. I'm willing to pay someone who's had experience building a few of these knobs, assuming his workmanship is good. I know when I do custom jobs like this, the second or third ones usually come out better than the first.